Karen Richardson

QUEBEC CITY — Oral misoprostol appears to be as effective as oxytocin by injection in reducing blood loss at delivery, but is associated with an increased need for additional oxytocic drugs, according to a randomized, controlled trial presented in poster format at the annual meeting of the Society of Obstetricians and Gynaecologists of Canada.

“Oral misoprostol may be used to reduce postpartum bleeding, particularly in areas where injectable oxytocic drugs are unavailable,” reported lead investigator Thomas Baskett, M.B., professor of obstetrics and gynecology at Dalhousie University in Halifax, Nova Scotia.

The synthetic PGE1 analogue has the advantage of being a cheap, stable, and orally administered uterotonic agent. “The main application for this is in developing countries, where they don't have personnel looking after women who can inject, or where there is no equipment or oxytocics to do so,” he said in an interview, adding that it might also have applications in rural communities if injectable oxytocics were not available.

Misoprostol has a role as second-line therapy if other injectables fail. “You might not use it routinely for active management of the third stage to reduce or prevent blood loss, but if bleeding occurs, then you can give misoprostol either orally or rectally with ease, and it's easy to have it stored in nursing stations or hospitals,” he said.

To assess efficacy of both agents, he and his colleagues compared 311 women given 400 mcg of oral misoprostol and 311 women who were given intravenous oxytocin, 5 units given after delivery of the anterior shoulder of the fetus. Researchers looked at women who had cephalic presentation and delivered vaginally, between 2000 and 2003 at the IWK Health Centre in Halifax. Those who had a multiple pregnancy, placenta previa, abruptio placentae, coagulation abnormalities, cesarean section, or severe asthma were excluded.

The primary outcome of at least a 10% drop in hematocrit at 24 hours' post partum was not clinically or statistically significantly different between the groups, and occurred in 10 of 291 (3.4%) of oxytocin patients, compared with 11 of 294 (3.7%) in the misoprostol group.

A total of 20 patients in the intravenous oxytocin group and 17 in the oral misoprostol group had missing hematocrit and hemoglobin values.

Of the secondary outcomes, 8.9% of oxytocin patients had a hematocrit drop of at least 30%, compared with 10.2% of patients in the misoprostol group.

Blood loss that was greater than 1,000 mL occurred in 2.3% of the oxytocin group and 4.5% of the misoprostol group. Additional uterotonics were required in 40.5% of those in the oxytocin group compared with 51.1% of those in the oral misoprostol group.

Researchers noted that the number of patients receiving additional oxytocics was high in both groups, and this was most likely due to the prevailing routine at the hospital of giving an intravenous infusion of oxytocin following the initial bolus dose at delivery.

Side effects of shivering and fever were present only in patients in the misoprostol group at the dose used, but were not clinically troublesome, the researchers noted. “Most of the trials that have found often upsetting shivering were with 600 mcg, and our study was with 400 mcg,” Dr. Baskett said in an interview.

The study was conducted to substantiate that it is reasonable to use the 400-mcg dose if the local circumstances and resources dictate that it be used, he noted.

QUEBEC CITY — Oral misoprostol appears to be as effective as oxytocin by injection in reducing blood loss at delivery, but is associated with an increased need for additional oxytocic drugs, according to a randomized, controlled trial presented in poster format at the annual meeting of the Society of Obstetricians and Gynaecologists of Canada.

“Oral misoprostol may be used to reduce postpartum bleeding, particularly in areas where injectable oxytocic drugs are unavailable,” reported lead investigator Thomas Baskett, M.B., professor of obstetrics and gynecology at Dalhousie University in Halifax, Nova Scotia.

The synthetic PGE1 analogue has the advantage of being a cheap, stable, and orally administered uterotonic agent. “The main application for this is in developing countries, where they don't have personnel looking after women who can inject, or where there is no equipment or oxytocics to do so,” he said in an interview, adding that it might also have applications in rural communities if injectable oxytocics were not available.

Misoprostol has a role as second-line therapy if other injectables fail. “You might not use it routinely for active management of the third stage to reduce or prevent blood loss, but if bleeding occurs, then you can give misoprostol either orally or rectally with ease, and it's easy to have it stored in nursing stations or hospitals,” he said.

To assess efficacy of both agents, he and his colleagues compared 311 women given 400 mcg of oral misoprostol and 311 women who were given intravenous oxytocin, 5 units given after delivery of the anterior shoulder of the fetus. Researchers looked at women who had cephalic presentation and delivered vaginally, between 2000 and 2003 at the IWK Health Centre in Halifax. Those who had a multiple pregnancy, placenta previa, abruptio placentae, coagulation abnormalities, cesarean section, or severe asthma were excluded.

The primary outcome of at least a 10% drop in hematocrit at 24 hours' post partum was not clinically or statistically significantly different between the groups, and occurred in 10 of 291 (3.4%) of oxytocin patients, compared with 11 of 294 (3.7%) in the misoprostol group.

A total of 20 patients in the intravenous oxytocin group and 17 in the oral misoprostol group had missing hematocrit and hemoglobin values.

Of the secondary outcomes, 8.9% of oxytocin patients had a hematocrit drop of at least 30%, compared with 10.2% of patients in the misoprostol group.

Blood loss that was greater than 1,000 mL occurred in 2.3% of the oxytocin group and 4.5% of the misoprostol group. Additional uterotonics were required in 40.5% of those in the oxytocin group compared with 51.1% of those in the oral misoprostol group.

Researchers noted that the number of patients receiving additional oxytocics was high in both groups, and this was most likely due to the prevailing routine at the hospital of giving an intravenous infusion of oxytocin following the initial bolus dose at delivery.

Side effects of shivering and fever were present only in patients in the misoprostol group at the dose used, but were not clinically troublesome, the researchers noted. “Most of the trials that have found often upsetting shivering were with 600 mcg, and our study was with 400 mcg,” Dr. Baskett said in an interview.

The study was conducted to substantiate that it is reasonable to use the 400-mcg dose if the local circumstances and resources dictate that it be used, he noted.

QUEBEC CITY — Oral misoprostol appears to be as effective as oxytocin by injection in reducing blood loss at delivery, but is associated with an increased need for additional oxytocic drugs, according to a randomized, controlled trial presented in poster format at the annual meeting of the Society of Obstetricians and Gynaecologists of Canada.

“Oral misoprostol may be used to reduce postpartum bleeding, particularly in areas where injectable oxytocic drugs are unavailable,” reported lead investigator Thomas Baskett, M.B., professor of obstetrics and gynecology at Dalhousie University in Halifax, Nova Scotia.

The synthetic PGE1 analogue has the advantage of being a cheap, stable, and orally administered uterotonic agent. “The main application for this is in developing countries, where they don't have personnel looking after women who can inject, or where there is no equipment or oxytocics to do so,” he said in an interview, adding that it might also have applications in rural communities if injectable oxytocics were not available.

Misoprostol has a role as second-line therapy if other injectables fail. “You might not use it routinely for active management of the third stage to reduce or prevent blood loss, but if bleeding occurs, then you can give misoprostol either orally or rectally with ease, and it's easy to have it stored in nursing stations or hospitals,” he said.

To assess efficacy of both agents, he and his colleagues compared 311 women given 400 mcg of oral misoprostol and 311 women who were given intravenous oxytocin, 5 units given after delivery of the anterior shoulder of the fetus. Researchers looked at women who had cephalic presentation and delivered vaginally, between 2000 and 2003 at the IWK Health Centre in Halifax. Those who had a multiple pregnancy, placenta previa, abruptio placentae, coagulation abnormalities, cesarean section, or severe asthma were excluded.

The primary outcome of at least a 10% drop in hematocrit at 24 hours' post partum was not clinically or statistically significantly different between the groups, and occurred in 10 of 291 (3.4%) of oxytocin patients, compared with 11 of 294 (3.7%) in the misoprostol group.

A total of 20 patients in the intravenous oxytocin group and 17 in the oral misoprostol group had missing hematocrit and hemoglobin values.

Of the secondary outcomes, 8.9% of oxytocin patients had a hematocrit drop of at least 30%, compared with 10.2% of patients in the misoprostol group.

Blood loss that was greater than 1,000 mL occurred in 2.3% of the oxytocin group and 4.5% of the misoprostol group. Additional uterotonics were required in 40.5% of those in the oxytocin group compared with 51.1% of those in the oral misoprostol group.

Researchers noted that the number of patients receiving additional oxytocics was high in both groups, and this was most likely due to the prevailing routine at the hospital of giving an intravenous infusion of oxytocin following the initial bolus dose at delivery.

Side effects of shivering and fever were present only in patients in the misoprostol group at the dose used, but were not clinically troublesome, the researchers noted. “Most of the trials that have found often upsetting shivering were with 600 mcg, and our study was with 400 mcg,” Dr. Baskett said in an interview.

The study was conducted to substantiate that it is reasonable to use the 400-mcg dose if the local circumstances and resources dictate that it be used, he noted.

QUEBEC CITY — Placental compensation may influence fetal growth in women with gestational hypertension, according to research presented at the annual meeting of the Society of Obstetricians and Gynaecologists of Canada.

“Pregnancies complicated by gestational hypertension and to a greater extent preeclampsia had significantly lower birth weight/placental weight ratios, compared with the controls at 38 and 39 weeks,” said Rebecca Cash, M.D., a resident in obstetrics and gynecology at the University of Toronto.

In the retrospective cohort study, Dr. Cash and her associates analyzed information on 12,422 term pregnancies (37–41 weeks) using data from the St. Joseph's Health Care, London perinatal database on births from Nov. 1, 1995 to November 1999. Singleton pregnancies complicated by gestational hypertension (1,084 cases), preeclampsia (144), or chronic hypertension (129) were compared with pregnancies in normotensive controls (11,065).

At 38 weeks, women with preeclampsia had significantly smaller babies than did controls (3,350 g vs. 3,520 g), whereas there was no significant difference in birth weight in infants born to women with gestational hypertension and controls.

“In preeclampsia, the reduction in the ratio indicates that the fetus is undergrown in relation to placental size, suggesting functional placental impairment,” Dr. Cash said.

Pregnancies complicated by gestational hypertension showed statistically significantly larger placenta weights vs. pregnancies in the control group at 38 and 39 weeks (692 g vs. 682 g, respectively), but not at 40 and 41 weeks.

Larger placenta size suggests there is a compensatory increase in placental weight for decreased function in gestational hypertension, which may influence fetal growth. “Abnormal placentation is thought to play a central role in the pathophysiology of preeclampsia,” said Dr. Cash. She added that this may have an effect on long-term outcomes, as findings of low birth weight and large placenta are independent risk factors for cardiovascular disease in adulthood.

In the study, gestational hypertension was defined as maternal blood pressure greater than 140/90 after 20 weeks' gestation without proteinuria. Preeclampsia was defined as maternal blood pressure greater than 140/90 after 20 weeks' gestation, accompanied by proteinuria or other end organ abnormalities. Chronic hypertension was defined as maternal blood pressure greater than 140/90 before 20 weeks' gestation.

Pregnancies complicated by diabetes, stillbirth, and congenital or chromosomal abnormalities were excluded from the analysis. Placental weights were routinely determined without trimming membranes or draining blood.

Dr. Cash's associate in the study was Rob Gratton, M.D., of the University of Western Ontario, London.

QUEBEC CITY — Placental compensation may influence fetal growth in women with gestational hypertension, according to research presented at the annual meeting of the Society of Obstetricians and Gynaecologists of Canada.

“Pregnancies complicated by gestational hypertension and to a greater extent preeclampsia had significantly lower birth weight/placental weight ratios, compared with the controls at 38 and 39 weeks,” said Rebecca Cash, M.D., a resident in obstetrics and gynecology at the University of Toronto.

In the retrospective cohort study, Dr. Cash and her associates analyzed information on 12,422 term pregnancies (37–41 weeks) using data from the St. Joseph's Health Care, London perinatal database on births from Nov. 1, 1995 to November 1999. Singleton pregnancies complicated by gestational hypertension (1,084 cases), preeclampsia (144), or chronic hypertension (129) were compared with pregnancies in normotensive controls (11,065).

At 38 weeks, women with preeclampsia had significantly smaller babies than did controls (3,350 g vs. 3,520 g), whereas there was no significant difference in birth weight in infants born to women with gestational hypertension and controls.

“In preeclampsia, the reduction in the ratio indicates that the fetus is undergrown in relation to placental size, suggesting functional placental impairment,” Dr. Cash said.

Pregnancies complicated by gestational hypertension showed statistically significantly larger placenta weights vs. pregnancies in the control group at 38 and 39 weeks (692 g vs. 682 g, respectively), but not at 40 and 41 weeks.

Larger placenta size suggests there is a compensatory increase in placental weight for decreased function in gestational hypertension, which may influence fetal growth. “Abnormal placentation is thought to play a central role in the pathophysiology of preeclampsia,” said Dr. Cash. She added that this may have an effect on long-term outcomes, as findings of low birth weight and large placenta are independent risk factors for cardiovascular disease in adulthood.

In the study, gestational hypertension was defined as maternal blood pressure greater than 140/90 after 20 weeks' gestation without proteinuria. Preeclampsia was defined as maternal blood pressure greater than 140/90 after 20 weeks' gestation, accompanied by proteinuria or other end organ abnormalities. Chronic hypertension was defined as maternal blood pressure greater than 140/90 before 20 weeks' gestation.

Pregnancies complicated by diabetes, stillbirth, and congenital or chromosomal abnormalities were excluded from the analysis. Placental weights were routinely determined without trimming membranes or draining blood.

Dr. Cash's associate in the study was Rob Gratton, M.D., of the University of Western Ontario, London.

QUEBEC CITY — Placental compensation may influence fetal growth in women with gestational hypertension, according to research presented at the annual meeting of the Society of Obstetricians and Gynaecologists of Canada.

“Pregnancies complicated by gestational hypertension and to a greater extent preeclampsia had significantly lower birth weight/placental weight ratios, compared with the controls at 38 and 39 weeks,” said Rebecca Cash, M.D., a resident in obstetrics and gynecology at the University of Toronto.

In the retrospective cohort study, Dr. Cash and her associates analyzed information on 12,422 term pregnancies (37–41 weeks) using data from the St. Joseph's Health Care, London perinatal database on births from Nov. 1, 1995 to November 1999. Singleton pregnancies complicated by gestational hypertension (1,084 cases), preeclampsia (144), or chronic hypertension (129) were compared with pregnancies in normotensive controls (11,065).

At 38 weeks, women with preeclampsia had significantly smaller babies than did controls (3,350 g vs. 3,520 g), whereas there was no significant difference in birth weight in infants born to women with gestational hypertension and controls.

“In preeclampsia, the reduction in the ratio indicates that the fetus is undergrown in relation to placental size, suggesting functional placental impairment,” Dr. Cash said.

Pregnancies complicated by gestational hypertension showed statistically significantly larger placenta weights vs. pregnancies in the control group at 38 and 39 weeks (692 g vs. 682 g, respectively), but not at 40 and 41 weeks.

Larger placenta size suggests there is a compensatory increase in placental weight for decreased function in gestational hypertension, which may influence fetal growth. “Abnormal placentation is thought to play a central role in the pathophysiology of preeclampsia,” said Dr. Cash. She added that this may have an effect on long-term outcomes, as findings of low birth weight and large placenta are independent risk factors for cardiovascular disease in adulthood.

In the study, gestational hypertension was defined as maternal blood pressure greater than 140/90 after 20 weeks' gestation without proteinuria. Preeclampsia was defined as maternal blood pressure greater than 140/90 after 20 weeks' gestation, accompanied by proteinuria or other end organ abnormalities. Chronic hypertension was defined as maternal blood pressure greater than 140/90 before 20 weeks' gestation.

Pregnancies complicated by diabetes, stillbirth, and congenital or chromosomal abnormalities were excluded from the analysis. Placental weights were routinely determined without trimming membranes or draining blood.

Dr. Cash's associate in the study was Rob Gratton, M.D., of the University of Western Ontario, London.

QUEBEC CITY — Women who've had a prior preterm birth are at increased risk for a subsequent preterm birth and associated neonatal morbidity and mortality, and this risk is inversely related to the gestational age at which their first spontaneous preterm birth occurred.

That finding emerged from a population-based cohort study of more than 25,000 women that was presented at the annual meeting of the Society of Obstetricians and Gynaecologists of Canada.

Women with a previous preterm birth, especially if it's earlier than 34 weeks, are at high risk and should be monitored carefully, said Erica Frecker, M.D., a resident in obstetrics and gynecology at Dalhousie University in Halifax, N.S., working under B. Anthony Armson, M.D.

The study offers useful information for obstetricians who give preconceptional counseling to women with previous preterm births, who are often worried about the outcome of their next pregnancy, said Dr. Frecker, the study's lead author.

Using the Nova Scotia Atlee Perinatal Database, researchers identified 25,525 women who had their first and second deliveries in 1988–2001. All of the women had spontaneous births; stillbirths and major fetal anomalies in the first pregnancy were excluded.

The women were categorized into four groups based on their babies' gestational ages at first delivery. The risks of preterm birth and serious neonatal morbidity or mortality in the subsequent pregnancy were calculated using multivariate analysis.

The incidence of preterm birth earlier than 37 weeks, earlier than 34 weeks, and earlier than 28 weeks was 4.66%, 1.25%, and 0.3%, respectively, in the first pregnancy, followed by an incidence of 3.66%, 0.94%, and 0.24%, respectively, in the second pregnancy.

The relative risk of having a preterm birth in the second pregnancy was inversely related to the gestational age at birth in the first pregnancy, except in the youngest gestational age category. (See chart.)

The numbers were adjusted for multiple gestation and uterine anomaly by multivariate regression.

The proportions of neonatal morbidity/mortality in the second pregnancy increased as the gestational age category decreased. The proportions increased from 1.21% for gestational ages greater than 37 weeks to 8.18% for gestational ages of less than 28 weeks. Serious neonatal morbidity cases included necrotizing enterocolitis, severe respiratory distress syndrome, bronchopulmonary dysplasia, sepsis, pneumonia, and meningitis.

Commenting on the study, David Young, M.D., past president of the Society of Obstetricians and Gynaecologists of Canada, noted that the results from the provincial perinatal database may be applicable to the general population, as they represent every birth in Nova Scotia for 1988–2001. “Researchers or clinicians in the field, particularly of preterm birth, would not be surprised by these results, but it adds substantially to the information that already is available and what might have been our best guess,” said Dr. Young, now head of the department of obstetrics and gynecology at Dalhousie University's IWK Health Centre in Halifax.

Although “we don't have a proven, effective method of intervention,” Dr. Young said, the study may shed light on the controversy surrounding intramuscular progesterone, which was the subject of several studies, including a randomized, controlled trial (N. Engl. J. Med 2003;348:2379–85). Since then, a more recent review has been published on the prevention of preterm delivery using the same medication (Obstet. Gynecol. 2005;105:1128–35).

“It [progesterone] may be the closest thing that might be effective,” Dr. Young said.

The study results also provide evidence that women who have a prior preterm birth—particularly those who delivered earlier than 34 weeks—should be monitored more closely, noted Dr. Young. These patients may be considered for investigations such as cervical length surveillance through transvaginal ultrasound, for the treatment of prophylactic steroids for lung maturity, and for modification of activity.

QUEBEC CITY — Women who've had a prior preterm birth are at increased risk for a subsequent preterm birth and associated neonatal morbidity and mortality, and this risk is inversely related to the gestational age at which their first spontaneous preterm birth occurred.

That finding emerged from a population-based cohort study of more than 25,000 women that was presented at the annual meeting of the Society of Obstetricians and Gynaecologists of Canada.

Women with a previous preterm birth, especially if it's earlier than 34 weeks, are at high risk and should be monitored carefully, said Erica Frecker, M.D., a resident in obstetrics and gynecology at Dalhousie University in Halifax, N.S., working under B. Anthony Armson, M.D.

The study offers useful information for obstetricians who give preconceptional counseling to women with previous preterm births, who are often worried about the outcome of their next pregnancy, said Dr. Frecker, the study's lead author.

Using the Nova Scotia Atlee Perinatal Database, researchers identified 25,525 women who had their first and second deliveries in 1988–2001. All of the women had spontaneous births; stillbirths and major fetal anomalies in the first pregnancy were excluded.

The women were categorized into four groups based on their babies' gestational ages at first delivery. The risks of preterm birth and serious neonatal morbidity or mortality in the subsequent pregnancy were calculated using multivariate analysis.

The incidence of preterm birth earlier than 37 weeks, earlier than 34 weeks, and earlier than 28 weeks was 4.66%, 1.25%, and 0.3%, respectively, in the first pregnancy, followed by an incidence of 3.66%, 0.94%, and 0.24%, respectively, in the second pregnancy.

The relative risk of having a preterm birth in the second pregnancy was inversely related to the gestational age at birth in the first pregnancy, except in the youngest gestational age category. (See chart.)

The numbers were adjusted for multiple gestation and uterine anomaly by multivariate regression.

The proportions of neonatal morbidity/mortality in the second pregnancy increased as the gestational age category decreased. The proportions increased from 1.21% for gestational ages greater than 37 weeks to 8.18% for gestational ages of less than 28 weeks. Serious neonatal morbidity cases included necrotizing enterocolitis, severe respiratory distress syndrome, bronchopulmonary dysplasia, sepsis, pneumonia, and meningitis.

Commenting on the study, David Young, M.D., past president of the Society of Obstetricians and Gynaecologists of Canada, noted that the results from the provincial perinatal database may be applicable to the general population, as they represent every birth in Nova Scotia for 1988–2001. “Researchers or clinicians in the field, particularly of preterm birth, would not be surprised by these results, but it adds substantially to the information that already is available and what might have been our best guess,” said Dr. Young, now head of the department of obstetrics and gynecology at Dalhousie University's IWK Health Centre in Halifax.

Although “we don't have a proven, effective method of intervention,” Dr. Young said, the study may shed light on the controversy surrounding intramuscular progesterone, which was the subject of several studies, including a randomized, controlled trial (N. Engl. J. Med 2003;348:2379–85). Since then, a more recent review has been published on the prevention of preterm delivery using the same medication (Obstet. Gynecol. 2005;105:1128–35).

“It [progesterone] may be the closest thing that might be effective,” Dr. Young said.

The study results also provide evidence that women who have a prior preterm birth—particularly those who delivered earlier than 34 weeks—should be monitored more closely, noted Dr. Young. These patients may be considered for investigations such as cervical length surveillance through transvaginal ultrasound, for the treatment of prophylactic steroids for lung maturity, and for modification of activity.

QUEBEC CITY — Women who've had a prior preterm birth are at increased risk for a subsequent preterm birth and associated neonatal morbidity and mortality, and this risk is inversely related to the gestational age at which their first spontaneous preterm birth occurred.

That finding emerged from a population-based cohort study of more than 25,000 women that was presented at the annual meeting of the Society of Obstetricians and Gynaecologists of Canada.

Women with a previous preterm birth, especially if it's earlier than 34 weeks, are at high risk and should be monitored carefully, said Erica Frecker, M.D., a resident in obstetrics and gynecology at Dalhousie University in Halifax, N.S., working under B. Anthony Armson, M.D.

The study offers useful information for obstetricians who give preconceptional counseling to women with previous preterm births, who are often worried about the outcome of their next pregnancy, said Dr. Frecker, the study's lead author.

Using the Nova Scotia Atlee Perinatal Database, researchers identified 25,525 women who had their first and second deliveries in 1988–2001. All of the women had spontaneous births; stillbirths and major fetal anomalies in the first pregnancy were excluded.

The women were categorized into four groups based on their babies' gestational ages at first delivery. The risks of preterm birth and serious neonatal morbidity or mortality in the subsequent pregnancy were calculated using multivariate analysis.

The incidence of preterm birth earlier than 37 weeks, earlier than 34 weeks, and earlier than 28 weeks was 4.66%, 1.25%, and 0.3%, respectively, in the first pregnancy, followed by an incidence of 3.66%, 0.94%, and 0.24%, respectively, in the second pregnancy.

The relative risk of having a preterm birth in the second pregnancy was inversely related to the gestational age at birth in the first pregnancy, except in the youngest gestational age category. (See chart.)

The numbers were adjusted for multiple gestation and uterine anomaly by multivariate regression.

The proportions of neonatal morbidity/mortality in the second pregnancy increased as the gestational age category decreased. The proportions increased from 1.21% for gestational ages greater than 37 weeks to 8.18% for gestational ages of less than 28 weeks. Serious neonatal morbidity cases included necrotizing enterocolitis, severe respiratory distress syndrome, bronchopulmonary dysplasia, sepsis, pneumonia, and meningitis.

Commenting on the study, David Young, M.D., past president of the Society of Obstetricians and Gynaecologists of Canada, noted that the results from the provincial perinatal database may be applicable to the general population, as they represent every birth in Nova Scotia for 1988–2001. “Researchers or clinicians in the field, particularly of preterm birth, would not be surprised by these results, but it adds substantially to the information that already is available and what might have been our best guess,” said Dr. Young, now head of the department of obstetrics and gynecology at Dalhousie University's IWK Health Centre in Halifax.

Although “we don't have a proven, effective method of intervention,” Dr. Young said, the study may shed light on the controversy surrounding intramuscular progesterone, which was the subject of several studies, including a randomized, controlled trial (N. Engl. J. Med 2003;348:2379–85). Since then, a more recent review has been published on the prevention of preterm delivery using the same medication (Obstet. Gynecol. 2005;105:1128–35).

“It [progesterone] may be the closest thing that might be effective,” Dr. Young said.

The study results also provide evidence that women who have a prior preterm birth—particularly those who delivered earlier than 34 weeks—should be monitored more closely, noted Dr. Young. These patients may be considered for investigations such as cervical length surveillance through transvaginal ultrasound, for the treatment of prophylactic steroids for lung maturity, and for modification of activity.