Updated: Apr 12
We've heard from two couples who conceived a child shortly after beginning a regular practice of deliberate cold exposure. Given the metabolic and hormonal benefits of the ice bath, perhaps the coincidence of ice bath and fertility are related. Nonetheless, once they realize their pregnancy, it's very natural of them to ask:
Is it OK for pregnant women to cold plunge?
To help find an answer, we turned to Josephine Worsek, PhD -- the only woman in Germany certified as a Wim Hof Instructor, and author of Die Heilkraft Der Kalte (or 'The Healing Power of the Cold' [in German], 2020).
She recently posted a picture of her pregnant sister wading into cold water outdoors, to demonstrate that ice bathing during pregnancy is "not a problem."
Worsek cautions that "Wim Hof breathing should not be performed by pregnant women."
She speculates a little about the advantages of deliberate cold exposure for conception, but she doesn't describe the potential benefits of cold plunging for women who are already pregnant -- and there may be several.
A recent study of pregnant Canadian women found that more than 1 in 5 were diagnosed with gestational diabetes and that the prevalence during the summer months exceeds that during winter months (Retnakaran et al. 2018) -- a finding reinforced by other studies that show greater cold exposure during the winter confers the benefit of increased insulin sensitivity, and lower blood glucose levels (e.g., Wainstock & Yoles 2018).
Another study, this time of over one million pregnant Chinese women, supports this idea. Those pregnant women with the greatest heat exposure suffered increased risk of pre-term birth, while the pregnant women with the greatest cold exposure enjoyed reduced risk of premature birth (Guo et al, 2017).
The benefits of a regular cold plunge may be particularly important for women in warmer climates. A study of Australian women discovered that exposure to heat waves can increase the risk of adverse birth outcomes, including still birth (Jiajia et al. 2019). The vulnerability to extreme heat may greatest during the first trimester, according to a review of the effects of temperature and pregnancy (McMurray & Katz 2012).
The same review concluded that cold exposure presents "minimal risk to the fetus," except in the extreme case in which hypothermia may be "detrimental to maternal survival" (ibid).
Given the benefits of cold exposure in general, and the risks of extreme heat, pregnant women might do will to continue to Forge, but avoid the sauna.
In addition to the metabolic benefits of deliberate cold exposure for pregnant women, there may be emotional and psychological benefits, too. One of the most recent studies on cold water swimming and women's health hypothesized: