The effect of body mass index (BMI) and gestational weight gain on adverse obstetrical outcomes in pregnancies following assisted reproductive technology as compared to spontaneously conceived pregnancies.

OBJECTIVE

To compare the effect of pre-pregnancy body mass index (BMI) and inappropriate gestational weight gain (GWG) on adverse obstetrical outcomes among women undergoing assisted reproductive technology (ART) treatments as compared to spontaneously-conceived (SC) pregnancies.

METHODS

This prospective cohort study included 1058 pregnant women from two medical centres; 504 women who conceived following ART treatments and 554 who conceived spontaneously. The women were recruited at 8 weeks of gestation and follow-up telephone interviews were conducted 6 weeks after delivery. Obstetrical outcomes included pregnancy hypertension, gestational diabetes (GD), low birth weight (LBW) (<2500g) and small for gestational age (SGA). Multivariate analyses were used to assess the effect of pre-pregnancy BMI and inappropriate GWG on these obstetrical outcomes adjusted for risk factors.

RESULTS

The effect of pre-pregnancy BMI and inappropriate GWG on adverse obstetrical outcomes did not differ between ART and SC pregnancies. Pre-pregnancy obesity was found to be associated with increased risk for pregnancy hypertension (OR=2.16; 95%CI 1.16-4.03), GD (OR=2.89; 95%CI 1.61-5.17), caesarian section (OR=1.77; 95%CI 1.10-2.85) and SGA (OR=1.91; 95%CI 1.05-3.46). GWG below recommendations was associated with increased risk for GD (OR=1.73; 95%CI 1.06-2.82) and SGA (OR=1.69; 95%CI 1.17-2.40) while GWG above recommendations was associated with increased risk for pregnancy hypertension (OR=1.77; 95%CI 1.02-3.06).

CONCLUSIONS

Pre-pregnancy obesity and inappropriate GWG were associated with adverse obstetrical outcomes in both ART and SC pregnancies. Emphasis should be given on the importance of an optimal pre-pregnancy BMI and appropriate GWG during pregnancy.