Longer commute time is associated with a higher risk of miscarriage: a mixed-effects longitudinal study.

Background: Long commuting has been linked to some adverse pregnancy outcomes, but its association with miscarriage, one of the most common pregnancy complications, has not been investigated. This study examined whether the frequency and duration of commuting are associated with miscarriage risk.

Methods: We used waves 1-11 (2008-2019) of the German Family Panel (Pairfam) and sampled women aged 16-45 who had a male partner, worked for pay, and reported a live birth or a miscarriage during the observation period. Cases of recurrent (3 or more) miscarriages were excluded. The final sample consisted of 579 women who reported 458 live births and 121 miscarriages. The association between commuting and miscarriage was examined using mixed effects logistic regression models, stepwise adjusting for work-related confounders.

Results: Commute time longer than 20 min one-way was associated with an increased risk of miscarriage (OR 1.98; CI: 1.00-3.90) compared to commute time under 10 min, in the sample of all commuters. The risk was overall highest for those who commuted daily and for longer than 30 min one-way (OR: 2.28; CI: 1.05-4.98). Commute frequency alone was not associated with an increased risk, but there might be selection into sporadic or no commuting.

Conclusions: A longer commute may represent a modifiable risk factor for miscarriage. Reducing commute time through home-based work, transport-related policies, or flexible scheduling to avoid peak hours could help mitigate this risk, particularly for women with an elevated baseline risk. Future studies should explore potential mechanisms linking commuting to adverse pregnancy outcomes, including stress, environmental exposures, and disruptions to circadian rhythms.