Pre-Pregnancy Obesity, Excessive Gestational Weight Gain, and the Risk of Pregnancy-Induced Hypertension and Gestational Diabetes Mellitus

Abstract

Excessive pre-pregnancy weight is a known risk factor of pregnancy complications. The purpose of this analysis was to assess the relationship between several categories of maternal weight and the risk of developing hypertension and diabetes in pregnancy, and the relationship of these complications with the results of the newborn. It was carried out in a common cohort of pregnant women and taking into account the influence of disturbing factors. Our analysis was conducted in a prospective cohort of 912 Polish pregnant women, recruited during 2015–2016. We evaluated the women who subsequently developed diabetes with dietary modification (GDM-1) (n = 125) and with insulin therapy (GDM-2) (n = 21), as well as the women who developed gestational hypertension (GH) (n = 113) and preeclampsia (PE) (n = 24), compared to the healthy controls. Odds ratios of the complications (and confidence intervals (95%)) were calculated in the multivariate logistic regression. In the cohort, 10.8% of the women had pre-pregnancy obesity (body mass index (BMI) ≥ 30 kg/m2), and 36.8% had gestational weight gain (GWG) above the range of the Institute of Medicine recommendation. After correction for excessive GWG and other confounders, pre-pregnancy obesity (vs. normal BMI) was associated with a higher odds ratio of GH (AOR = 4.94; p < 0.001), PE (AOR = 8.61; p < 0.001), GDM-1 (AOR = 2.99; p < 0.001), and GDM-2 (AOR = 11.88; p <0.001). The threshold risk of development of GDM-2 occurred at lower BMI values (26.9 kg/m2), compared to GDM-1 (29.1 kg/m2). The threshold point for GH was 24.3 kg/m2, and for PE 23.1 kg/m2. For GWG above the range (vs. GWG in the range), the adjusted odds ratios of GH, PE, GDM-1, and GDM-2 were AOR = 1.71 (p = 0.045), AOR = 1.14 (p = 0.803), AOR = 0.74 (p = 0.245), and AOR = 0.76 (p = 0.672), respectively. The effect of maternal edema on all the results was negligible. In our cohort, hypertension and diabetes were associated with incorrect birth weight and gestational age at delivery. Conclusions: This study highlights the importance and influence of excessive pre-pregnancy maternal weight on the risk of pregnancy complications such as diabetes and hypertension which can impact fetal outcomes.

The Influence of Maternal BMI on Adverse Pregnancy Outcomes in Older Women

“…Interestingly, in our study, older age increased the risk of both macrosomia (>4000 g) and LBW (<2500 g). This effect is similar to the effect of maternal obesity on both high and low birth weight (Supplement Table S2) [16].…”

“…PE and IUGR often coexist, and in their pathogenesis the role of placental ischemia in early pregnancy is taken into account. The risk profiles of PE and preterm birth may also be similar, since the completion of pregnancy (with placental and fetal delivery) remains the primary treatment for preeclampsia (PE) and preterm birth is an important adverse effect of PE [16,17]. The risk profile for SGA was similar (although not identical) to that for IUGR, but we want to emphasize that we defined SGA as <10th percentile (according to percentile grids for gender and gestational age in the study population) and IUGR neonates were pathologically small being both in the <10th percentile and in the newborn group between the 10th and 90th percentile.…”

“…All these changes (factors) may increase the risk of hypertension and diabetes in pregnancy. Maternal metabolic disturbances, obesity, diabetes, and hypertension all contribute to higher odds ratios of neonatal macrosomia and/or LBW (LGA and SGA), and are likely an important link between older age (>35 years) and these neonatal outcomes [16]. On the other hand, it is thought that both physiological and organ immaturity is the main factor responsible for the increased risk of some adverse events in pregnancy at an early age.…”

“…Gestational diabetes mellitus (GDM) was diagnosed on the basis of an (2-h) oral glucose tolerance test (75 g) at 24-28 weeks of gestation [16].…”

“…One of the key elements in the pathogenesis of adverse pregnancy outcomes (such as hypertension, diabetes, premature birth, or fetal growth restriction) is increased oxidative stress. A higher risk of these pregnancy complications has been associated with lower levels of antioxidants [10][11][12][13][14][15][16]. This suggests that the oxidative stress associated with aging may increase the risk of pregnancy complications.…”