Association between job control and time to pregnancy in a preconception cohort.

Objective: To evaluate associations between low job control (operationalized as job independence and freedom to make decisions) and time to pregnancy. Low job control, a form of workplace stress, is associated with adverse health outcomes ranging from cardiovascular disease to premature mortality; few studies have specifically examined its association with reproductive outcomes.

Design: We used data from Pregnancy Study Online, an internet-based preconception cohort study of couples trying to conceive in the United States and Canada. We estimated fecundability ratios (FRs) and 95% confidence intervals (CIs) via proportional probability regression models, adjusting for sociodemographic and behavioral characteristics.

Setting: Not applicable (Web-based study).

Patients: Participants self-identified as female, were aged 21-45 years, and reported ≤6 cycles of pregnancy attempt time at enrollment (2018-2022).

Exposure: We assessed job control by matching participants' baseline self-reported occupation and industry with standardized occupation codes from the National Institute for Occupational Safety and Health's Industry and Occupation Computerized Coding System, then linking codes to O∗NET job exposure scores for job independence and freedom to make decisions.

Main Outcome Measure: Our main outcome measure was fecundability. Participants completed self-administered questionnaires at baseline and every 8 weeks for up to 12 months or until reported pregnancy, whichever occurred first.

Results: Among 3,110 participants, lower job independence was associated with reduced fecundability. Compared with the fourth (highest) quartile, corresponding to the most job independence, FRs (95% CI) for first (lowest), second, and third quartiles were 0.92 (0.82-1.04), 0.84 (0.74-0.95), and 0.99 (0.88, 1.11), respectively. Lower freedom to make decisions was associated with slightly reduced fecundability (first vs. fourth quartile: FR = 0.92; 95% CI: 0.80-1.05).

Conclusion: Lower job control, a work-related stressor, may adversely influence time to pregnancy. Because job control is a condition of work (i.e., not modifiable by individuals), these findings may strengthen arguments for improving working conditions as a means of improving worker health, including fertility.