Should We Focus on a Women’s Weight During Pregnancy?

As any woman who has ever been pregnant knows, there is an intense focus on weight throughout pregnancy. From the first visit with your OB when you step on the scale and are given a prescription for how much weight to gain, all the way through the postpartum period when your body is scrutinized for how fast you drop the baby weight, pregnancy can be a difficult time for even the most body confident woman. For those struggling with body image dissatisfaction, yo-yo dieting, or other disordered eating, what is supposed to be one of the happiest times in a woman’s life can be a nightmare.

Did you know that many countries don’t provide weight-based guidelines for pregnancy? For example, in the UK, women are simply advised to eat healthy and exercise. Other countries focus on overall health while in the US we obsess about the numbers on the scale. Lest you think that this focus on weight is providing a foundation for superior maternal health, I should note that the US has the worst maternal health out of any developed country.

The US Institute of Medicine (IOM) sets specific guidelines for weight gain during pregnancy based on a woman’s pre-pregnancy BMI. Women who meet BMI criteria for “obesity” are restricted to a weight gain of just 11-20 lbs during their pregnancy. When you consider that the average newborn weighs 8 lbs, there are 2 lbs of amniotic fluid, and the placenta weighs 1 ½ lbs, plus all of the increased fluid, larger uterus and breasts, etc…this is essentially a recommendation for women to lose weight. Many pregnant women gain weight outside of the IOM’s recommended range. While this is associated with negative maternal and child outcomes, few studies parse out the effect of weight gain from nutrition and physical activity. Many healthcare providers feel pressure to monitor and limit their patients’ weight gain during pregnancy, which in turn may increase a pregnant woman’s own concerns about weight gain during pregnancy. The irony of weight-focused care is that the more preoccupied we become with trying to control our weight, the more out-of-control it often becomes. The boundary model of eating behavior suggests that restrained eating leads to overeating in disinhibited states. Restriction leads to overeating and stress effects our metabolism. We often end up engaging in unhealthy behaviors to try and achieve a certain number on the scale.

A study by Heery et al (2016) set out to determine if pre-pregnancy restrained eating behaviors (defined as the conscious effort to restrict food intake to control body weight) and early pregnancy attitudes to weight gain were associated with weight gain during pregnancy outside the IOM guidelines. Results indicated that, in early pregnancy, 72% of women were ‘a little’ or moderately worried about weight gain and 64% were ‘a little’ or moderately worried about changes in body shape and size during pregnancy. Increased levels of concern about weight gain and concern about changes in body shape and size were associated with higher total gestational weight gain (GWG) and higher odds of excessive weight gain. Restrained eating, weight cycling (a pattern of losing and gaining weight), and dieting were each independently associated with higher absolute GWG. Weight cycling was associated with weight gain in excess of the IOM guidelines. Dietary restraint and concerns about weight gain were associated with GWG irrespective of BMI, suggesting that these issues affect women across the weight spectrum. The authors conclude that concerns about weight gain, concerns about changes in body shape and size, and a history of weight cycling predicts weight gain during pregnancy in excess of IOM recommendations.

Policing women’s bodies during pregnancy is not working. Our singular obsession with weight comes at the expense of health. Pregnancy is a vulnerable time for women, one in which we need support from our health professionals to accept our changing bodies, minimize stress, and work towards holistic wellbeing. Health is about so much more than the numbers on the scale.