Is using a heating blanket bad while trying to conceive (TTC)?

Using Heating Blankets While Trying to Conceive (TTC)

Using a heating blanket while trying to conceive may potentially be harmful to male fertility, though the evidence regarding female fertility is less conclusive.

Effects on Male Fertility

• Heat exposure is a concern for male fertility, as animal studies strongly suggest an adverse effect of heat on spermatogenesis and subsequent fertility 1
• It is well established that increased testicular temperature can negatively impact sperm production, as seen in conditions like cryptorchidism where testes are exposed to core body temperature 1
• Occupational heat exposure has been identified as a significant risk factor for male infertility, affecting sperm morphology and potentially resulting in delayed conception 2
• The quality of evidence linking heat to human male infertility is relatively poor, with most studies having limitations such as small sample sizes, lack of control groups, and confounding factors 1
• Studies show that activities increasing scrotal temperature (like saunas, hot baths) may affect semen parameters, though the reported reductions are often small and may still be within normal ranges 1

Effects on Female Fertility and Pregnancy

• Electric blanket use at the time of conception and in early pregnancy may be associated with a slight increase in risk of pregnancy loss, though the evidence is not strong 3
• A study examining electric blanket use found an unadjusted relative risk of 1.84 (95% CI = 1.08-3.13) for spontaneous abortion, which decreased slightly to 1.74 (95% CI = 0.96-3.15) after adjustment for other factors 3
• While hot tub and sauna exposure in early pregnancy have been associated with increased risk of neural tube defects, electric blanket use specifically showed a much weaker association (RR 1.2,95% CI 0.5-2.6) 4
• Extreme heat exposure during pregnancy may trigger earlier delivery among term births, with stronger associations for early-term (37-38 weeks) than full-term (≥39 weeks) deliveries 5

Recommendations for Couples TTC

• For men trying to conceive, it is advisable to avoid excessive heat exposure to the scrotal area, which could include prolonged use of heating blankets, especially at high settings 1, 2
• For women, while the evidence is less conclusive, it may be prudent to use heating blankets cautiously during the conception period and early pregnancy 3, 4
• If using a heating blanket is necessary for comfort:
  • Use lower temperature settings 1, 4
  • Avoid prolonged continuous use, especially for men 1, 2
  • Consider using the blanket to warm the bed before sleeping rather than keeping it on throughout the night 1

Common Pitfalls and Caveats

• The evidence regarding heating blankets specifically (as opposed to general heat exposure) and fertility is limited 1
• Many studies on heat exposure and fertility suffer from methodological limitations including small sample sizes, lack of control groups, and inconsistent definitions of heat exposure 1
• Temperature effects may vary based on duration of exposure, intensity of heat, and individual factors 1
• While avoiding excessive heat is a reasonable precaution when trying to conceive, other factors such as age, overall health, and other lifestyle factors likely have more significant impacts on fertility 1