# McMaster University Study Links Excessive Gestational Weight Gain to Severe Morbidity Risk

- Published: 2026-11-10 09:47 UTC
- Section: Life & Health › Medicine
- Tags: gestational weight gain, severe maternal morbidity, body mass index categories, maternal health risk, McMaster University Medical Center
- URL: https://realtech.media/news/rt-3949745e9d02dbe0c1d7e817_mcmaster_university_study/

**An analysis of over one million singleton pregnancies showed that weight gain outside guideline ranges is linked to elevated rates of severe maternal morbidity.**

![McMaster University Study Links Excessive Gestational Weight Gain to Severe Morbidity Risk](https://realtech.media/media/2026/11/7875b2c13467dd27.webp)
*endocrinologyadvisor.com*

Gestational weight gain outside recommended ranges was associated with increased risks of severe maternal morbidity, according to researchers from McMaster University Medical Center in Hamilton, Ontario, Canada. The population-based cohort study, published online in *JAMA Network Open* and reported by endocrinologyadvisor.com, analyzed clinical records from nearly 1.04 million singleton pregnancies documented between April 1, 2012, and March 31, 2022 [1].

## Morbidity Rates Across Weight Categories

Among the studied cohort, 52.8 percent of pregnancies involved excessive gestational weight gain, and 15,119 individuals experienced severe maternal morbidity, establishing a baseline frequency of 14.59 cases per 1,000 births [1]. Excessive gain was linked to higher morbidity rates across all prepregnancy body mass index categories when compared with adequate weight gain. The adjusted rate ratios were 1.33 for individuals classified as underweight, 1.24 for normal weight, 1.16 for overweight, 1.21 for class I obesity, 1.28 for class II obesity, and 1.24 for class III obesity [1].

## Nonlinear Risk Distributions

Inadequate gestational weight gain was also linked to increased rates of maternal morbidity, predominantly among individuals with normal weight (adjusted rate ratio, 1.13) and those with overweight (adjusted rate ratio, 1.19) [1]. The researchers observed nonlinear associations between weight gain and maternal complications across all evaluated categories. While risks were elevated at both low and high extremes of weight gain for individuals who were underweight, normal weight, and overweight prior to pregnancy, the elevated risk for cohorts with class I to III obesity was concentrated primarily at high weight gain levels [1].

## Sources

1. [endocrinologyadvisor.com](https://www.endocrinologyadvisor.com/news/excessive-gestational-weight-gain-linked-to-severe-maternal-morbidity)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-3949745e9d02dbe0c1d7e817_mcmaster_university_study/