I’ve lost count of how many times I’ve heard from pregnant clients that they’ve had a triggering, dismissive experience at a prenatal appointment where they were instructed to limit their future weight gain. Most pregnant people enter pregnancy feeling anxious about how their body will change. The last thing they need is to be told their body is changing in the wrong way, especially when those changes already feel out of control.

I want to acknowledge that very few perinatal providers intend to cause harm when they bring up concerns about pregnancy weight gain. Everyone wants to support positive outcomes for both the pregnant person and the baby. The American College of Obstetricians and Gynecologists establishes recommended guidelines for how much weight to gain throughout pregnancy, broken down by BMI category. The assumption underlying prenatal care is that gaining weight outside of these guidelines is harmful.

I’ve taken issue with these guidelines for as long as I’ve known about them. We already know that BMI is a poor predictor of health status and an unhelpful way to categorize people. But it turns out, there’s a much bigger issue with pregnancy weight gain guidelines that rarely gets discussed: the evidence simply doesn’t support that preventing excess weight gain improves outcomes. Research does show, however, that the emphasis on control can cause harm.

Let’s dive in.

The Assumption We’re Operating From

Most prenatal care follows the assumption that weight gain outside of the recommended ranges is likely to lead to worse outcomes. The observational data shows associations between higher weight gain and complications like gestational diabetes, preeclampsia, cesarean delivery, and macrosomia (having a large baby). Based on these associations, the logic goes: if we can control weight gain, we should be able to prevent these complications.

It’s a logical assumption. But here’s the problem: it doesn’t hold up when researchers actually test it.

The Observational Evidence and Its Limitations

All the pregnancy weight gain outcome data we have comes from observational studies. This means researchers have tracked individuals through pregnancy, monitored weight changes, and documented any complications that arose. These studies show associations between weight gain outside the recommendations and poorer outcomes. But association doesn’t equal causation.

To prove that weight gain itself causes poor outcomes, we would need to control for every other variable that might influence both weight gain and pregnancy complications. In practice, this is nearly impossible to do.

There are many factors that correlate with both prenatal weight gain and pregnancy outcomes, and any of these could be influencing outcomes independently:

  • Socioeconomic factors and chronic stress
  • Food insecurity and healthcare access
  • Weight stigma and quality of care received
  • Pre-existing health conditions
  • What someone is actually eating versus their weight
  • Sleep quality, movement patterns, and mental health
  • The physiological and psychological stress of restriction itself

When observational studies don’t adequately account for these confounding variables, we can’t know whether weight gain is driving outcomes or whether it’s simply a marker for other underlying factors.

What Happens When We Actually Intervene

If weight gain itself were the problem, we’d expect a clear pattern: studies that successfully reduce gestational weight gain should show improved pregnancy outcomes. This is where randomized controlled trials come in. Unlike observational studies, RCTs can test whether interventions to control weight gain actually work.

So what does this research show?

The findings are striking and consistent.

The 2017 International Weight Management in Pregnancy Study

Researchers analyzed data from over 12,000 pregnant women across 36 studies. Diet and exercise programs successfully reduced how much weight women gained during pregnancy. But here’s what didn’t change: rates of preeclampsia, gestational diabetes, or preterm birth remained the same between groups. The only notable difference was a modest reduction in cesarean sections.

In other words, even though the interventions achieved their goal of limiting weight gain, this didn’t translate into the health improvements we would expect if excess weight gain were truly the problem.

The Story Gets More Telling

In 2021, researchers followed up with the children from these studies. The conventional belief is that controlling prenatal weight gain reduces childhood obesity risk. But when researchers checked in with these children at ages 3-5, they found something different: these kids weren’t any less likely to be above the 90th percentile for weight than children whose mothers hadn’t participated in the interventions.

If maternal weight gain were driving childhood obesity, we’d expect to see a difference here. We didn’t.

A Comprehensive 2015 Cochrane Review

This review found similar results. While diet and exercise programs reduced excessive weight gain by 20%, they didn’t clearly improve outcomes like preeclampsia, cesarean delivery, or preterm birth. More concerning, women in these programs were significantly more likely to gain too little weight — raising the question of whether our focus on limiting weight gain is creating new problems.

This Matters Because Inadequate Weight Gain Carries Its Own Risks

In a large study of over 120,000 pregnant women with obesity, those who gained less than the recommended 15 pounds had a significantly higher risk of delivering a small-for-gestational-age infant. The research revealed a troubling trade-off: lower weight gain reduced some risks (preeclampsia, cesarean delivery, large babies) while simultaneously increasing others (small babies). There’s no sweet spot where controlling weight consistently improves all outcomes.

Perhaps Most Telling

A 2021 meta-review examining multiple systematic reviews found that interventions for women with higher weights reduced gestational weight gain by only 1.4 to 2 pounds on average — and showed no demonstrated impact on pregnancy or infant health outcomes. The review also noted that nearly all of these studies were conducted in high-income countries, raising important questions: Are we focusing on weight when we should be addressing socioeconomic factors, stress, healthcare access, and quality of care?

What This Evidence Gap Tells Us

Here’s the bottom line: if weight gain itself were causing poor outcomes, limiting it should improve those outcomes. The research shows we can reduce weight gain. But we’re not seeing the health improvements we’d expect. This gap between our ability to control weight and our inability to improve outcomes suggests we’ve been intervening on the wrong thing.

The Harms of Overemphasis on Weight Control

We’re not talking nearly enough about the harm caused when we focus so heavily on gestational weight gain that we lose sight of what actually supports healthy pregnancies.

When prenatal appointments center on weight and controlling the number on the scale, there are real consequences. I see the impact of these conversations nearly every day in my practice.

Clients reach out to me distressed after their prenatal providers express concern about their weight gain. The patterns I observe include:

  • Food restriction and inadequate nutrition
  • Triggering or worsening disordered eating behaviors
  • Increased body preoccupation and anxiety
  • Loss of trust in one’s body and hunger cues
  • Worsening mental health, including increased anxiety, depression, and OCD symptoms

These aren’t minor side effects. They’re serious harms that directly undermine both physical and mental health during pregnancy.

Sarah’s Story

Sarah lives in a larger body and has a BMI above 30, which means standard recommendations suggest she gain 11-20 pounds during pregnancy. She has a history of stigmatizing experiences in medical settings, so she tends to avoid doctor’s appointments. With an irregular menstrual cycle, she doesn’t realize she’s pregnant until she’s four months along.

When Sarah finally establishes care with an OB, she’s met with judgment from office staff and alarm from her providers. They tell her she’s already gained 12 pounds and is at high risk for complications. Despite her history of an eating disorder, they encourage her to limit further weight gain by avoiding carbs and minimizing snacking.

Sarah is already stressed about an unplanned pregnancy. Now she’s terrified that her body will fail her and that her providers will be disappointed if she can’t follow their recommendations. The very care meant to help her is instead recreating the food anxiety and restriction she worked so hard to overcome.

What’s Really Going On Here

Sarah’s story isn’t unique. And there are several factors in her situation that are far more likely to contribute to pregnancy complications than her weight changes:

  • Delayed prenatal care due to previous weight stigma and medical trauma
  • Stress and anxiety triggered by the response to her weight
  • Food restriction that may lead to inadequate nutrition
  • Mental health impacts of renewed eating disorder behaviors
  • Eroded trust between Sarah and her healthcare providers

When we fixate on weight, we miss opportunities to address what actually matters: adequate nutrition, stress reduction, consistent prenatal care, and mental health support. Worse, the weight-focused intervention itself becomes a source of harm.

What Actually Supports Healthy Pregnancies

If controlling weight gain isn’t the answer, what is? The good news is that there are many evidence-based ways to support healthy pregnancies that don’t require obsessing over the scale.

Adequate, Regular Nourishment

Rather than restricting food or following rigid rules, pregnant people benefit from eating consistently throughout the day and responding to hunger cues. This means having regular meals and snacks that include a variety of foods — carbohydrates, proteins, fats, fruits, and vegetables. Adequate nutrition supports fetal growth, maternal energy, and stable blood sugar, all of which contribute to better outcomes. And all of these improved outcomes can exist outside of any potential impacts on weight.

Joyful, Gentle Movement

Movement during pregnancy doesn’t need to be about burning calories or controlling weight. Instead, focus on activities that feel good and are sustainable — walking, swimming, prenatal yoga, or simply stretching. Movement can improve mood, reduce stress, support sleep quality, and help manage common pregnancy discomforts.

Quality Sleep and Stress Management

Sleep and stress have profound impacts on pregnancy health, affecting everything from blood pressure to glucose metabolism to immune function. Supporting pregnant people in getting adequate rest and managing stress –whether through therapy, mindfulness practices, social support, or simply saying “no” more often — is crucial for wellbeing.

Consistent Prenatal Monitoring

Regular prenatal care allows providers to track what actually matters: blood pressure, blood sugar levels, fetal growth and movement, and other vital signs. These metrics give us real-time information about how pregnancy is progressing and allow for early intervention if concerns arise. Unlike weight, these are markers we can directly connect to specific health outcomes.

Mental Health Support

Pregnancy and postpartum mental health significantly impact both maternal and infant outcomes. Screening for anxiety, depression, and trauma, and connecting pregnant people with appropriate support, should be a routine part of prenatal care. This is especially important given that weight-focused care can trigger or worsen mental health symptoms.

Addressing Social Determinants of Health

The factors that most strongly predict pregnancy outcomes often have nothing to do with individual behavior: stable housing, food security, financial stability, access to healthcare, experiences of discrimination, and community support all matter enormously. When we focus exclusively on weight, we ignore these critical social and structural factors.

Weight-Inclusive, Stigma-Free Care

Perhaps most importantly, pregnant people deserve care that treats them with respect and dignity regardless of their body size. This means providers asking about eating patterns and concerns before making assumptions, acknowledging the limits of weight as a health indicator, and recognizing that weight stigma itself is harmful to health. It means creating an environment where all pregnant people feel safe seeking care.

These Are Things We Can Actually Support

Here’s what makes these approaches different from weight control: we can meaningfully support people in each of these areas. We can provide nutrition education that emphasizes adequacy rather than restriction. We can connect people with mental health resources. We can monitor health markers that give us actionable information. We can advocate for policies that address social determinants of health.

What we can’t do, and what the research confirms we shouldn’t try to do, is control how much weight someone gains during pregnancy and expect that control to improve outcomes. It’s time to redirect our energy toward what actually makes a difference.

Moving Forward

Of course, standard prenatal care hasn’t caught up to this more nuanced understanding of weight and pregnancy outcomes. Weight-focused, stigmatizing care is still far too common. But we can shift our approach to more effective, meaningful practices.

I truly believe that all providers want good outcomes for their patients. The emphasis on weight usually doesn’t come from a place of malice — it comes from a genuine desire to help patients have healthy pregnancies, positive birth experiences, and smooth postpartum recoveries. The problem is that we’ve been operating from flawed assumptions about what creates those outcomes.

We can actually improve outcomes by shifting our focus to what the evidence supports: helping people nourish their bodies adequately, manage stress, find joyful movement, support their mental health, and address socioeconomic factors that threaten wellbeing. These are the interventions that make a difference.

Here’s what I keep coming back to: we need to stop causing harm in the name of prevention. Weight-focused interventions, delivered with the best intentions, are breaking trust, triggering disordered eating, and creating the very stress and restriction that undermine health. When we focus on controlling weight instead of supporting actual health behaviors, we’re solving the wrong problem, and creating new ones in the process.

Our patients deserve better. They deserve care grounded in evidence, free from weight stigma, and focused on what actually promotes wellbeing for them and their babies.

If You’re Struggling

If you’re pregnant and feeling anxious about weight gain, or if you’ve had a distressing experience with a provider who focused heavily on the number on the scale, please know: your body is not the problem. Weight gain during pregnancy is normal, necessary, and largely not within your control. You deserve care that supports your whole health — physical, mental, and emotional — not care that leaves you feeling stressed, restricted, or afraid to trust your body.

If you’re experiencing disordered eating, food preoccupation, or anxiety around eating during pregnancy, support is available. You don’t have to navigate this alone, and you absolutely don’t have to choose between your mental health and your pregnancy health.

I specialize in supporting pregnant and postpartum people through exactly these concerns. If you’d like to explore working together, you can learn more about my services HERE or schedule a free clarity call HERE.

For Providers

If you’re a perinatal provider who wants to move toward more evidence-based, weight-inclusive care but aren’t sure where to start, I’m here to support you. I offer consultation services for OBs, midwives, and other perinatal clinicians who want to:

  • Better understand the evidence around gestational weight gain
  • Learn how to have productive conversations about nutrition without focusing on weight control
  • Identify and address eating disorders and disordered eating during pregnancy
  • Provide trauma-informed, weight-inclusive prenatal care
  • Collaborate effectively with dietitians and mental health providers

Shifting our approach to prenatal weight takes intention, but it’s absolutely possible—and our patients deserve nothing less. If you’re interested in learning more or would like to discuss how we might work together to better support your patients, please reach out HERE.

Together, we can create prenatal care that truly supports health.

References

International Weight Management in Pregnancy (i-WIP) Collaborative Group. Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials. BMJ. 2017;358:j3119. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6887834/

The effects of dietary and lifestyle interventions among pregnant women with overweight or obesity on early childhood outcomes: an individual participant data meta-analysis from randomised trials. BMC Medicine. 2021;19:154. https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-021-01995-6

Muktabhant B, Lawrie TA, Lumbiganon P, Laopaiboon M. Diet or exercise, or both, for preventing excessive weight gain in pregnancy. Cochrane Database of Systematic Reviews. 2015;(6):CD007145. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD007145.pub3/full

Kiel DW, Dodson EA, Artal R, Boehmer TK, Leet TL. Gestational weight gain and pregnancy outcomes in obese women: how much is enough? Obstetrics & Gynecology. 2007;110(4):752-758. https://pubmed.ncbi.nlm.nih.gov/17906005/

Fair FJ, et al. A meta-review of systematic reviews of lifestyle interventions for reducing gestational weight gain in women with overweight or obesity. Obesity Reviews. 2021;22(5):e13199. https://onlinelibrary.wiley.com/doi/10.1111/obr.13199

Haakstad LAH, Voldner N, Henriksen T, Bø K. Why do pregnant women stop exercising in the third trimester? Acta Obstetricia et Gynecologica Scandinavica. 2009;88(11):1267-1275. (Norwegian Fit for Delivery RCT) https://pubmed.ncbi.nlm.nih.gov/26768233/Lifestyle Interventions for Expectant Moms (LIFE-Moms) Consortium. Design of lifestyle intervention trials to prevent excessive gestational weight gain in women with overweight or obesity. Contemporary Clinical Trials. 2015;41:227-237. https://pmc.ncbi.nlm.nih.gov/articles/PMC4731277/