Obesity a driving factor in stillbirth

NEW ORLEANS – Almost 20% of the stillbirths that occurred over an 8-year period appeared to be associated with obesity.

A database review of nearly 3 million births found that the risk of stillbirth increased along with body mass index and gestational age. For women with the highest BMI – 50 kg/m² – the incidence of a stillbirth jumped from 1.8/1,000 pregnancies at 39 weeks to 3/1,000 at 40 weeks and to more than 5/1,000 by 41 weeks, Dr. Ruofan Yao reported at the annual Pregnancy Meeting sponsored by the Society for Maternal-Fetal Medicine.

"There is a dose-response relationship where the greater the BMI, the higher the risk of stillbirth. Obesity is a major contributing risk for stillbirth, where 20% of all stillbirths happen to women who are obese, and 1 in 4 stillbirths after 37 weeks is associated with obesity," said Dr. Yao of Drexel University, Philadelphia. "This is significantly higher than the population-attributable risk for chronic hypertension or pregestational diabetes."

Dr. Yao used birth and death records from Texas and Washington to determine the associations between weight and stillbirth. The Texas cohort included data on about 2 million births that occurred from 2006 to 2011. The Washington cohort included data on about 1 million from 2003 to 2011. Of the nearly 3 million births analyzed, about 9,000 were stillbirths. Fetuses with severe congenital anomalies were excluded from the analysis, as were pregnancies with a gestational age of less than 20 weeks.

Overall, 51% of the mothers in the analysis were of normal weight. About a quarter were overweight. Class I obesity was present in 13%, class II in 6%, and class III in 3.5%. The remaining 0.5% had a BMI of 50 or higher.

Although the risk of stillbirth rose with BMI and gestational age, overweight women were at no significantly increased risk of stillbirth compared with normal-weight women.

Women in class I were about twice as likely to have a stillbirth at both 37-39 weeks and 40-42 weeks. For women in class II, the risk was about 2.5 times higher at 37-39 weeks and twice as high at 40-42 weeks. In class III, the risk of stillbirth was three times higher at both time points.

The risk was sharply elevated for women with a BMI of 50 or more. At 37-39 weeks, they had a threefold increased risk. That jumped to a ninefold increased risk by 40-42 weeks, Dr. Yao said.

A separate analysis quantified population-attributable risk (PAR) for obesity and stillbirth. For all obesity (30 or higher), the risk was almost 20% overall. The PAR was 24% for early-term pregnancies and 28% for late-term pregnancies.

"Furthermore, over 5% of stillbirths from 37-39 weeks were associated with the much smaller subset of women who are morbidly obese, and this number jumps to 8% from 40-42 weeks," he said.

"Our data pointed to 39 weeks as a pivotal point in the pregnancy where the risk of stillbirth increases at a dramatic pace for women with BMI more than 50," Dr. Yao said in an interview. "I believe it is reasonable to have a discussion with patients in this BMI group regarding their maternal and fetal risks for expectant management verses delivery at 39 weeks. Whether to extend this recommendation to other obese women is unclear until more studies can delineate the risks and benefits more clearly."

The pathophysiology behind the association of obesity and preterm birth isn’t yet clear, he added.

"It is known in endocrine and medicine literature that obesity increases the baseline inflammatory response, and this may lead to abnormal placental growth and the development of uteroplacental insufficiency," Dr. Yao said.

"Obesity is also commonly associated with sleep apnea, which often worsens in pregnancy and can lead to transient hypoxic state, hindering normal fetal growth, and increase the risk of preeclampsia. Obesity also leads to glucose intolerance and increased serum lipid and triglyceride levels, leading to accelerated fetal growth velocity, and may contribute to the development of uteroplacental insufficiency. Additionally, the dietary habits of many obese women tend to exacerbate that problem."

Dr. Yao reported that he had no financial disclosures.

[email protected]

NEW ORLEANS – Almost 20% of the stillbirths that occurred over an 8-year period appeared to be associated with obesity.

A database review of nearly 3 million births found that the risk of stillbirth increased along with body mass index and gestational age. For women with the highest BMI – 50 kg/m² – the incidence of a stillbirth jumped from 1.8/1,000 pregnancies at 39 weeks to 3/1,000 at 40 weeks and to more than 5/1,000 by 41 weeks, Dr. Ruofan Yao reported at the annual Pregnancy Meeting sponsored by the Society for Maternal-Fetal Medicine.

"There is a dose-response relationship where the greater the BMI, the higher the risk of stillbirth. Obesity is a major contributing risk for stillbirth, where 20% of all stillbirths happen to women who are obese, and 1 in 4 stillbirths after 37 weeks is associated with obesity," said Dr. Yao of Drexel University, Philadelphia. "This is significantly higher than the population-attributable risk for chronic hypertension or pregestational diabetes."

Dr. Yao used birth and death records from Texas and Washington to determine the associations between weight and stillbirth. The Texas cohort included data on about 2 million births that occurred from 2006 to 2011. The Washington cohort included data on about 1 million from 2003 to 2011. Of the nearly 3 million births analyzed, about 9,000 were stillbirths. Fetuses with severe congenital anomalies were excluded from the analysis, as were pregnancies with a gestational age of less than 20 weeks.

Overall, 51% of the mothers in the analysis were of normal weight. About a quarter were overweight. Class I obesity was present in 13%, class II in 6%, and class III in 3.5%. The remaining 0.5% had a BMI of 50 or higher.

Although the risk of stillbirth rose with BMI and gestational age, overweight women were at no significantly increased risk of stillbirth compared with normal-weight women.

Women in class I were about twice as likely to have a stillbirth at both 37-39 weeks and 40-42 weeks. For women in class II, the risk was about 2.5 times higher at 37-39 weeks and twice as high at 40-42 weeks. In class III, the risk of stillbirth was three times higher at both time points.

The risk was sharply elevated for women with a BMI of 50 or more. At 37-39 weeks, they had a threefold increased risk. That jumped to a ninefold increased risk by 40-42 weeks, Dr. Yao said.

A separate analysis quantified population-attributable risk (PAR) for obesity and stillbirth. For all obesity (30 or higher), the risk was almost 20% overall. The PAR was 24% for early-term pregnancies and 28% for late-term pregnancies.

"Furthermore, over 5% of stillbirths from 37-39 weeks were associated with the much smaller subset of women who are morbidly obese, and this number jumps to 8% from 40-42 weeks," he said.

"Our data pointed to 39 weeks as a pivotal point in the pregnancy where the risk of stillbirth increases at a dramatic pace for women with BMI more than 50," Dr. Yao said in an interview. "I believe it is reasonable to have a discussion with patients in this BMI group regarding their maternal and fetal risks for expectant management verses delivery at 39 weeks. Whether to extend this recommendation to other obese women is unclear until more studies can delineate the risks and benefits more clearly."

The pathophysiology behind the association of obesity and preterm birth isn’t yet clear, he added.

"It is known in endocrine and medicine literature that obesity increases the baseline inflammatory response, and this may lead to abnormal placental growth and the development of uteroplacental insufficiency," Dr. Yao said.

"Obesity is also commonly associated with sleep apnea, which often worsens in pregnancy and can lead to transient hypoxic state, hindering normal fetal growth, and increase the risk of preeclampsia. Obesity also leads to glucose intolerance and increased serum lipid and triglyceride levels, leading to accelerated fetal growth velocity, and may contribute to the development of uteroplacental insufficiency. Additionally, the dietary habits of many obese women tend to exacerbate that problem."

Dr. Yao reported that he had no financial disclosures.

[email protected]

NEW ORLEANS – Almost 20% of the stillbirths that occurred over an 8-year period appeared to be associated with obesity.

A database review of nearly 3 million births found that the risk of stillbirth increased along with body mass index and gestational age. For women with the highest BMI – 50 kg/m² – the incidence of a stillbirth jumped from 1.8/1,000 pregnancies at 39 weeks to 3/1,000 at 40 weeks and to more than 5/1,000 by 41 weeks, Dr. Ruofan Yao reported at the annual Pregnancy Meeting sponsored by the Society for Maternal-Fetal Medicine.

"There is a dose-response relationship where the greater the BMI, the higher the risk of stillbirth. Obesity is a major contributing risk for stillbirth, where 20% of all stillbirths happen to women who are obese, and 1 in 4 stillbirths after 37 weeks is associated with obesity," said Dr. Yao of Drexel University, Philadelphia. "This is significantly higher than the population-attributable risk for chronic hypertension or pregestational diabetes."

Dr. Yao used birth and death records from Texas and Washington to determine the associations between weight and stillbirth. The Texas cohort included data on about 2 million births that occurred from 2006 to 2011. The Washington cohort included data on about 1 million from 2003 to 2011. Of the nearly 3 million births analyzed, about 9,000 were stillbirths. Fetuses with severe congenital anomalies were excluded from the analysis, as were pregnancies with a gestational age of less than 20 weeks.

Overall, 51% of the mothers in the analysis were of normal weight. About a quarter were overweight. Class I obesity was present in 13%, class II in 6%, and class III in 3.5%. The remaining 0.5% had a BMI of 50 or higher.

Although the risk of stillbirth rose with BMI and gestational age, overweight women were at no significantly increased risk of stillbirth compared with normal-weight women.

Women in class I were about twice as likely to have a stillbirth at both 37-39 weeks and 40-42 weeks. For women in class II, the risk was about 2.5 times higher at 37-39 weeks and twice as high at 40-42 weeks. In class III, the risk of stillbirth was three times higher at both time points.

The risk was sharply elevated for women with a BMI of 50 or more. At 37-39 weeks, they had a threefold increased risk. That jumped to a ninefold increased risk by 40-42 weeks, Dr. Yao said.

A separate analysis quantified population-attributable risk (PAR) for obesity and stillbirth. For all obesity (30 or higher), the risk was almost 20% overall. The PAR was 24% for early-term pregnancies and 28% for late-term pregnancies.

"Furthermore, over 5% of stillbirths from 37-39 weeks were associated with the much smaller subset of women who are morbidly obese, and this number jumps to 8% from 40-42 weeks," he said.

"Our data pointed to 39 weeks as a pivotal point in the pregnancy where the risk of stillbirth increases at a dramatic pace for women with BMI more than 50," Dr. Yao said in an interview. "I believe it is reasonable to have a discussion with patients in this BMI group regarding their maternal and fetal risks for expectant management verses delivery at 39 weeks. Whether to extend this recommendation to other obese women is unclear until more studies can delineate the risks and benefits more clearly."

The pathophysiology behind the association of obesity and preterm birth isn’t yet clear, he added.

"It is known in endocrine and medicine literature that obesity increases the baseline inflammatory response, and this may lead to abnormal placental growth and the development of uteroplacental insufficiency," Dr. Yao said.

"Obesity is also commonly associated with sleep apnea, which often worsens in pregnancy and can lead to transient hypoxic state, hindering normal fetal growth, and increase the risk of preeclampsia. Obesity also leads to glucose intolerance and increased serum lipid and triglyceride levels, leading to accelerated fetal growth velocity, and may contribute to the development of uteroplacental insufficiency. Additionally, the dietary habits of many obese women tend to exacerbate that problem."

Dr. Yao reported that he had no financial disclosures.

[email protected]