From the Journals

Prepregnancy obesity linked to bump in severe morbidity


Key clinical point: Prepregnancy BMI outside the normal range was linked to risk for maternal complications and death.Major finding: Severe morbidity and mortality risk was increased by 20% in women with prepregnancy class 2 obesity and 40% in women with class 3 obesity.

Study details: Retrospective analysis of 743,630 singleton pregnancies in Washington state between 2004 and 2013.

Disclosures: The study was funded by the Canadian Institutes of Health Research. Dr. Lisonkova is supported by an award from the Michael Smith Foundation for Health Research. No other financial disclosures were reported.

Source: Lisonkova S et al. JAMA. 2017 Nov 14;318(18):1777-86.


There is a link between obesity and maternal complications during pregnancy, but a causal relationship has not been established. It could be that obese women are inherently at greater risk of mortality, or it could be that physicians have a harder time managing severe conditions in women who are obese.

One way to better understand the problem is to study obesity and severe maternal morbidity in pregnant women because the severe morbidity may precede and add to the increased mortality rates that are being seen among obese pregnant women.

The results of the current study support the idea that the association between class 3 obesity and severe complications in pregnancy may play a role in the increased risk of maternal mortality that was also observed.

The results also suggest that physicians caring for women of childbearing age should emphasize the importance of achieving optimal body mass index in reducing pregnancy complications.

Aaron B. Caughey, MD, PhD, is the chair of the department of obstetrics and gynecology at Oregon Health and Science University, Portland. His comments are adapted from an accompanying editorial (JAMA. 2017;318[18]:1765-6). Dr. Caughey reported having no financial disclosures.



Having a high or low prepregnancy body mass index was associated with a small absolute increase in severe maternal morbidity and mortality in a large, retrospective cohort study.

Some studies have suggested a link between obesity and pregnancy complications such as preeclampsia, gestational diabetes, thromboembolism, and cesarean delivery. But one study suggested no link between higher BMI and risk of severe morbidity.

To address the question, the researchers analyzed data from 743,630 women who had singleton hospital births at 20-45 weeks’ gestation between 2004 and 2013 in Washington state. In all, 49.3% of women were overweight or obese, 47.5% had a normal BMI, and 3.2% were underweight. Just under half of women (47%) had weight gain during pregnancy that was higher than the recommended amount, while 19% had weight gain that was lower than recommended.

Adjustment for weight gain had no significant effect on the observed associations, Sarka Lisonkova, MD, PhD, of B.C. Women’s Hospital & Health Centre in Vancouver and her colleagues reported in JAMA.

Compared with normal weight women (BMI 18.5-24.9), women considered underweight (BMI less than 18.5) had an adjusted odds ratio (aOR) for mortality or severity morbidity of 1.2 (95% confidence interval, 1.0-1.3). Women who were overweight (BMI of 25.0-29.9) had an aOR of 1.1 (95% CI, 1.1-1.2).

The risk was also greater for women with class 1 obesity (BMI, 30.0-34.9; aOR, 1.1; 95% CI, 1.1-1.2), class 2 obesity (BMI, 35.0-39.9; aOR, 1.2; 95% CI, 1.1-1.3), and class 3 obesity (BMI, 40 or greater; aOR, 1.4; 95% CI, 1.3-1.5).

In all cases, the absolute increases in mortality and severe morbidity, compared with normal weight women, were small, ranging from adjusted rated differences of 17.6 per 10,000 for overweight women to 61.1 per 10,000 women with class 3 obesity. Underweight women had an increase of 28.8 per 10,000.

Specifically, underweight women had a higher risk for antepartum and postpartum hemorrhage and acute renal failure, whereas women who were obese had increased risks for respiratory morbidity and thromboembolism, the researchers reported.

The study was funded by the Canadian Institutes of Health Research. Dr. Lisonkova is supported by an award from the Michael Smith Foundation for Health Research. No other financial disclosures were reported.

SOURCE: Lisonkova S et al. JAMA. 2017 Nov 14;318(18):1777-86.

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