Does Obesity Increase the Risk of Miscarriage?

Researchers at the UCD Centre for Human Reproduction at the Coombe Women’s & Infants’ University Hospital are investigating the relationship between obesity and spontaneous miscarriage.  Professor Michael Turner and his research team compared the incidence of spontaneous miscarriage in women categorised as obese (based on a Body Mass Index >29.9 kg/m²) with women in other BMI categories.

Their prospective observational study enrolled 1200 women in the first trimester after a sonogram confirmed an ongoing singleton pregnancy with fetal heart activity present.  Maternal height and weight were measured digitally and BMI calculated. Maternal body composition was measured by advanced bioelectrical impedance analysis.

In 1200 women, the overall miscarriage rate was 2.8% (n=33). The mean gestational age at enrolment was 9.9 weeks. In the obese category (n=217), the miscarriage rate was 2.3% compared with 3.3% in the overweight category (n=329), and 2.3% in the normal BMI group (n=621). There was no difference in the mean body composition parameters, particularly fat mass parameters, between those women who miscarried and those who did not.

In women with sonographic evidence of fetal heart activity in the first trimester, the rate of spontaneous miscarriage is low and is not increased in women with BMI>29.9 kg/m(2) compared to women in the normal BMI category.

Reference: Eur J Obstet Gynecol Reprod Biol. 2010 Aug;151(2):168-70. Epub 2010 May 21.

Influence of Paternal Obesity

Researchers at UCD Centre for Human Reproduction have also looked at the implication of paternal obesity on subsequent offspring obesity. Their research programme measured the Body Mass Index (BMI) in 167 men whose partner was booking at the Coombe Women’s & Infants’ University Hospital for antenatal care. Of the men, 14% were obese compared with 16% of mothers-to-be. In addition, 50% were overweight and only one in three had a normal BMI.  The researchers also used advanced Bioelectrical Impedance Analysis to measure body composition.

While the percentage of body fat was higher in women, as expected, the visceral fat was higher in men (p<0.001). Visceral fat levels have been positively associated with an increased risk of cardiovascular disease in adults.  In addition, 32% of the men smoked and 81% consumed alcohol.

These findings raise important public health concerns for men regarding obesity.

• Do men need preconceptual care?
• Is pregnancy a window of opportunity to advise men, as well as women, about lifestyle issues such as diet, exercise and smoking?
• Are public health interventions more likely to succeed if they embrace both parents and the family unit rather than individuals?

Minimising male obesity is important not only for the individual, but also for his family. If he remains in good health, a father is better able to care for his family in the short-term and long-term. If the father is obese, there is also a 2-4 fold increase in obesity in his offspring. Breaking the cycle of obesity is important for future generations.

Reference 

Kelly RE, Farah N, O’Connor N, Kennelly MM, Stuart B, Turner MJ. A comparison of maternal and paternal body mass index during early pregnancy. Aust N Z J Obstet Gynaecol 2011;51:147-50

“Mums-to-be should optimise their weight before and during pregnancy because their weight affects blood sugar levels which in turn can cause overgrowth of the baby in the womb,” says Prof Fionnuala McAuliffe (Professor of Obstetrics and Gynaecology at the National Maternity Hospital, Holles Street, Dublin) who led the study.

The findings published online in the European Journal of Obstetrics, Gynecology and Reproductive Biology show that even small variations in blood sugar levels during pregnancy can influence the growth of the baby in the womb.

Funded by the Health Research Board in Ireland, the UCD researchers observed 479 healthy mother and infant pairs attending the National Maternity Hospital.  According to the findings, women with blood sugar concentrations at the upper end of the normal scale at 28 weeks of pregnancy were 3.5 times more likely to give birth to babies weighing over 9 pounds and 15 ounces (4500g) than those women with the lowest levels of blood sugar.  The average weight of a newborn baby is between 6 and 8 pounds. Babies born above 9 pounds and 15 ounces (4,500 grams) are considered larger babies.

“To optimise their weight mums-to-be should avoid too many high sugar foods such as white bread, cakes, soft drinks, fruit juices, and take regular exercise,” says Professor McAuliffe.

The study examined the association between maternal blood sugar levels throughout pregnancy and the growth of the baby in the womb, and the characteristics of the baby after birth.

“When the babies were born, we measured their weight, length, head circumference, and the level of cord blood glucose. The findings show that mother’s blood sugar levels influenced birth weight, but not the length or head size of the baby,” concludes Dr Jennifer Walsh who co-authored the study.

The researchers caution that the study findings do not suggest that all babies born above 9 pounds and 15 ounces (4500g) will suffer from childhood obesity.