SMFM: BMI Matters in Pregnancy

Discourage the fat from reproducing - keep women and babies safe.

For instance, women whose body mass index (BMI) exceeded 25, classifying them as overweight, had a risk ratio for cesarean section of 1.37 (95% CI 1.23 to 1.52) compared with women with a normal BMI, according to Tamula M. Patterson, MD, and colleagues from the University of Alabama in Birmingham...

"Prepregnancy weight and excessive weight gain during pregnancy may have an adverse effect on perinatal outcomes as well as a lasting effect on women's health," the researchers cautioned in a poster session at the annual meeting of the Society for Maternal-Fetal Medicine.

Among women of reproductive age, 57% are overweight and almost one-third are obese. In an attempt to quantify the maternal and fetal morbidities associated with different levels of BMI, Patterson's group looked at pregnancies among 18,057 women between 2000 and 2009...

With increasing BMI, the likelihood of most adverse outcomes was greater. For instance, with cesarean section, the risk ratio increased for obese women, whose BMI ranged from 30 to 39.9, to 1.86 (95% CI 1.68 to 2.05), and to 2.84 (95% CI 2.49 to 3.24) for morbidly obese women, whose BMI was 40 or higher (P for trend <0.0001).

For gestational diabetes, the risk ratios according to BMI were:

Underweight, 1.20 (95% CI 0.55 to 2.64)
Overweight, 1.97 (95% CI 1.47 to 2.65)
Obese, 3.95 (95% CI 3.02 to 5.17)
Morbidly obese, 5.30 (95% CI 3.88 to 7.24, P for trend <0.0001)
For other maternal outcomes, similar findings were seen. The risk ratio for gestational hypertension rose from 1.65 (95% CI 1.34 to 2.03) for overweight women to 3.54 (95% CI 2.80 to 4.46) for those who were morbidly obese (P for trend <0.0001).

And the risk for preeclampsia increased from 1.29 (95% CI 1.08 to 1.55) among the overweight to 2.76 (95% CI 2.24 to 3.41, P for trend <0.0001) among the morbidly obese.

Adverse fetal outcomes also were affected by excess maternal weight, such as neonatal birth weight being above 4,000 g:

Overweight, RR 1.83 (95% CI 1.50 to 2.22)
Obese, RR 2.37 (95% CI 1.96 to 2.87)
Morbidly obese, RR 3.33 (95% C 2.63 to 4.22, P for trend <0.0001)
Among women of childbearing age, inadequate emphasis is placed on the importance of achieving a normal weight before becoming pregnant, and then maintaining optimal nutritional status during and after pregnancy, the researchers stated.

"Thus, interventions are warranted to promote a normal BMI to decrease adverse consequences in pregnant women and their infants," they concluded.

Lose the weight.

Then have the kid.