Imagine carrying a new life inside you, but the extra pounds you gain during pregnancy could be putting both you and your baby at serious risk—it’s a reality that’s far more common than most people realize, and it’s time we talked about it openly.
Did you know that in about two out of every three pregnancies, women end up gaining weight that’s either too much or too little compared to what’s considered healthy? This imbalance isn’t just a number on the scale; it can lead to some scary complications, like babies being born too early (preterm birth), newborns who are unusually large (which we’ll explain more about shortly), or even needing urgent care in the neonatal intensive care unit right after birth. These insights come straight from a major systematic review led by researchers at Monash University, who sifted through data from a whopping 1.6 million women worldwide. The results were recently published in the prestigious medical journal, The BMJ, shining a light on a global health challenge we can’t ignore.
Let’s break down what gestational weight gain—or GWG, as experts call it—really means. It’s the total increase in body weight that happens during pregnancy, which includes growth for both the mom and the developing baby. But when it’s outside the recommended sweet spot, it ramps up the chances of problems for everyone involved. For beginners, think of it like this: just as you wouldn’t want to overfill or underfill a car’s gas tank before a long trip, your body needs the right amount of nourishment to support a smooth pregnancy journey.
Globally, we’re seeing around 130 million babies born each year, but here’s the kicker—in a world flooded with processed foods, sedentary lifestyles, and environmental factors that make healthy eating tougher, we’re in the middle of an epidemic where excessive GWG is becoming the norm. It’s like our modern food systems are stacked against us, pushing more women into risky territory without even realizing it.
Dr. Rebecca Goldstein, the lead author from the Monash Centre for Health Research and Implementation (MCHRI), couldn’t stress enough how urgent this is. In her words, “These results really drive home the importance of creating international benchmarks for what counts as healthy weight gain during pregnancy, paired with practical lifestyle advice and broader public health strategies. This could make a world of difference for moms and their little ones everywhere.”
But here’s where it gets controversial: most countries today still follow the gestational weight gain guidelines put out by the Institute of Medicine back in the day. The catch? Those were mostly based on studies of white women from wealthy nations in the 1980s. Fast-forward to now, and they just don’t cut it for the diverse mix of people across low-, middle-, and high-income countries, or account for how our food environments have shifted dramatically—think more fast food and less fresh options—which is fueling higher body mass indexes (BMI) around the globe. Is it fair to apply outdated standards to everyone, regardless of background? That’s a question that sparks debate among health experts.
In a smart move to address this, the World Health Organization (WHO) has kicked off a project to craft new, global standards for healthy GWG. These would tailor recommendations to fit different populations and settings, ensuring they’re relevant today. To back this up, the Monash team teamed up with WHO collaborators to dive into 40 high-quality observational studies from 2009 to 2024. These involved over 1.6 million women aged 18 or older, hailing from five out of the six WHO-defined world regions. The studies tracked pregnancy outcomes based on starting BMI and how much weight was gained, with 36 of them earning top marks for reliability.
Breaking down the numbers: Roughly half (53%) of the women started pregnancy with a healthy BMI, while 6% were underweight, 19% overweight, and 22% in the obese category. Shockingly, only about a third (32%) managed to stay within the suggested GWG range—23% gained too little, and a hefty 45% gained too much. And this is the part most people miss: even small deviations can snowball into big issues, like how a few extra pounds might seem harmless but could tip the scales toward complications.
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Diving into the risks using WHO’s BMI standards, gaining less weight than recommended linked to some upsides—like a lower chance of needing a C-section, having a baby who’s large for their gestational age (meaning bigger than average for how far along the pregnancy is), or dealing with macrosomia (that’s when a baby weighs over 8 pounds 13 ounces at birth, which can make delivery trickier). But on the flip side, it raised the odds of preterm birth (before 37 weeks), small-for-gestational-age babies (who might need extra help to grow properly), low birth weight, and even breathing problems like respiratory distress right after birth. For example, a preterm baby might face challenges like underdeveloped lungs, which is why catching this early matters so much.
On the other hand, gaining more than recommended was tied to heavier babies and a greater likelihood of C-sections, plus pregnancy complications like high blood pressure issues (hypertensive disorders). It also increased risks of macrosomia and NICU stays but seemed to offer a bit of protection against preterm birth and small babies. Interestingly, when researchers applied Asian-specific BMI categories in studies from that region, the patterns held pretty steady—showing these issues aren’t limited to one group.
Of course, no study is perfect, and the team acknowledged a few hurdles. Things like inconsistent ways of measuring BMI or GWG across studies could muddy the waters, and there weren’t enough quality studies from low-income countries, which means the data might not fully capture global diversity. Plus, they couldn’t completely discount hidden influences, such as whether women smoked, their age, or ethnic backgrounds, which might have played a role in the outcomes.
Still, Professor Helena Teede, the senior author and Director of the Monash Centre for Health Research and Implementation—as well as an endocrinologist at Monash Health—sees this as a clear call to action. She explained, “What we’ve uncovered here backs up the push for refined, evidence-driven WHO guidelines on GWG, drawn from real patient stories and suited to today’s varied populations around the world. This isn’t just an update; it’s a step up from what’s out there now, and it spotlights the urgent need for support at every level—from policies and healthcare systems to personal guidance—to boost health for mothers and babies globally.”
She went on to add that while these standards are a great foundation, they should feed into personalized care plans that avoid shaming women and instead focus on positive, tailored strategies. For instance, a doctor might combine GWG advice with nutrition counseling or light exercise tips suited to each person’s life. In the end, the heavy toll on health that this research reveals demands we step up with solutions across the board—whether through better policies, improved medical support, or empowering women individually—for the sake of moms and the next generation.
Now, here’s a controversial twist to ponder: Should we rethink how we even talk about weight in pregnancy to avoid adding stress that could worsen outcomes, or is tough love with strict guidelines the only way to protect health? What do you think—have you experienced GWG challenges, or do current guidelines feel outdated to you? Drop your thoughts in the comments; I’d love to hear your take and spark some real conversation on this vital topic.
Source:
Journal reference:
Goldstein, R. F., et al. (2025). Gestational weight gain and risk of adverse maternal and neonatal outcomes in observational data from 1.6 million women: systematic review and meta-analysis. BMJ. doi: 10.1136/bmj-2025-085710. https://www.bmj.com/content/391/bmj-2025-085710