Being overweight or underweight before pregnancy was associated with a small increased risk of severe maternal illness or death, according to research by the UBC Faculty of Medicine.
Unhealthy weight during pregnancy is associated with adverse birth outcomes. Less is known about the association between unhealthy weight before pregnancy and maternal complications.
Sarka Lisonkova
The observational study, led by Assistant Professor of Obstetrics and Gynaecology Sarka Lisonkova and published Nov. 14 in JAMA, followed 743,630 women in Washington State between 2004 and 2013.
Compared to women with normal body mass index (BMI) of 18.5-24.9, absolute risks of severe maternal illness or death per 10,000 women were 28.8 more for underweight women (BMI less than 18.5) and 61.1 more for obese women with a BMI of 40 or greater.
Severe maternal illness or death is defined as life-threatening conditions or conditions leading to serious consequences, or complications requiring intensive care unit admission, or maternal death during the hospitalization.
Underweight women had an increased risk of antepartum and postpartum hemorrhage with blood transfusion and renal failure, and were more likely to require a potentially lifesaving intervention.
The risk for overweight women was correlated with BMI – the higher the BMI, the higher the risk. For women with a BMI of 25 to 29.9, the absolute risk was 17.6 more per 10,000 women; for women with a BMI between 30 and 34.9, it was 24.9 more; and for women with a BMI of 35 to 39.9, it was 35.8 more.
Obese women had higher rates of pre-term birth or small-for-gestational-age birth, hypertension in pregnancy, and gestational diabetes. Obese women statistically significantly higher rates of thromboembolism, cerebrovascular morbidity, sepsis, acute renal failure, complications of obstetric interventions, respiratory morbidity, eclampsia, cardiac morbidity, and ICU admission.
On the other hand, women in the most obese category (BMI of 40 or higher) had significantly lower rates of severe antepartum and postpartum hemorrhage requiring transfusion.