What’s the relationship between obesity and pregnancy complications? Biostatisticians break down the link between a BMI over 30 and what to expect when you are expecting.
Obese pregnant women have higher risks of complications during pregnancy and at birth compared to non-obese pregnant women including gestational diabetes mellitus (GDM), preeclampsia, and emergency caesarian sections. All obese pregnant women are medically grouped into the high-risk category and follow identical care pathways, regardless of individual maternal characteristics. Not all high-risk pregnancies should be treated equally, however, and the care provided to obese pregnant women throughout their pregnancies should vary based on each woman’s individual characteristics to avoid pregnancy complications.
What Maternal Characteristics Contribute to Uncomplicated Pregnancies?
Medical professionals can improve care for obese pregnant women by understanding the maternal characteristics that contribute to an uncomplicated pregnancy. In a study published in BMC Medicine, researchers identified maternal characteristics that are associated with uncomplicated pregnancy and birth. Further, researchers demonstrate their ability to accurately predict an obese person’s risk of pregnancy complications based on individual factors. The ability to predict pregnancy outcomes is important in informing a pregnant woman’s care plan and can improve a woman’s chance of having an uncomplicated pregnancy.
The researchers collected data from 1,409 obese pregnant women regarding sociodemographic, clinical characteristics, and body measurements at 15-18 weeks gestation. They defined obesity as having a body mass index greater than 30 kg/m2. The researchers also collected data for maternal age, ethnicity, smoking, history of miscarriages, blood glucose levels, blood adiponectin levels (a protein involved in blood sugar levels and the breakdown of fatty acids), and more. All women were followed up on at 27 weeks, 34-35 weeks, delivery, and six months postpartum.
Obesity and pregnancy complications
Based on individual maternal characteristics, the women were stratified into five groups indicating their predicted risk of pregnancy complications. The researchers found that 64% of obese pregnant women experienced complications, with gestational diabetes mellitus and emergency caesarian section being the most common complications during pregnancy and at birth, respectively.
Five independent factors able to predict a low risk of complications in early pregnancy were identified: multiparity (having already had children), maternal age, systolic blood pressure, Hba1c levels (indicative of blood sugar), and adiponectin levels. Importantly, the obese pregnant women placed in the lowest risk group for pregnancy complications based on their maternal characteristics had the least incidences of complications. Further, women in the highest risk group for pregnancy complications had the highest prevalence of GDM (43%) and other pregnancy complications.
Accurately Evaluation of Individual Women is Necessary
These results showed that about one-third of all obese women had no pregnancy complications. Instead of grouping all obese pregnant women into a high-risk pregnancy category, gathering maternal characteristics of pregnant women allows an accurate evaluation of the actual risk level of pregnancy complications. For example, women who are at a high-risk for experiencing complications during pregnancy or at birth due to high systolic blood pressure may benefit from early management and additional blood pressure measurements. A risk assessment that includes maternal characteristics for obesity and pregnancy complications has the potential to improve clinical management and provide more choices for women, allowing women to have control of their own pregnancies.
Written by Mallory Wiggans
Reference: Vieira, M.C. et al. Prediction of uncomplicated pregnancies in obese women: a prospective multicentre study. BMC Medicine (2017) 15:194. DOI: 10.1186/s12916-017-0956-8