Association of income and education with fecundability in a North American preconception cohort

Abstract

Purpose: The purpose of this study is to evaluate socioeconomic determinants of fecundability.

Methods: Among 8654 female pregnancy planners from Pregnancy Study Online, a North American prospective cohort study (2013-2019), we examined associations between socioeconomic status and fecundability (the per-cycle probability of conception). Information on income and education was collected via baseline questionnaires. Bimonthly follow-up questionnaires were used to ascertain pregnancy status. We estimated fecundability ratios (FRs) and 95% confidence intervals (CIs) using proportional probabilities regression, controlling for potential confounders.

Results: Relative to an annual household income of greater than or equal to $150,000, adjusted FRs were 0.91 (95% CI: 0.83-1.01) for less than $50,000, 0.99 (95% CI: 0.92-1.07) for $50,000-$99,000, and 1.09 (95% CI: 1.01-1.18) for $100,000-$149,000. FRs for less than 12, 13-15, and 16 years of education, relative to greater than or equal to 17 years, were 0.90 (95% CI: 0.76-1.08), 0.84 (95% CI: 0.78-0.91), and 0.89 (95% CI: 0.84-0.95), respectively. Slightly stronger associations for income and education were seen among older women.

Conclusions: Lower levels of education and income were associated with modestly reduced fecundability. These results demonstrate the presence of socioeconomic disparities in fecundability.

Keywords: Education; Fecundability; Income; Social determinants of health; Socioeconomic status; Time to pregnancy.

Figure 1.. Restricted cubic spline^a and 95% CI showing the association between educational attainment and fecundability, with knots at 10%, 50%, and 90%, PRESTO, North America, 2013–2019.

^aSpline adjusted for age, race/ethnicity, income, BMI, smoking, physical activity, male partner education, last method of contraception, cycle length, intercourse frequency, history of sexually transmitted infection, doing something to improve chances of pregnancy, PSS score, MDI score, sleep duration, employment status, hours worked per week, and Healthy Eating Index score.

Figure 2.. Restricted cubic spline^a and 95% CI showing the association between household income and fecundability, with knots at 10%, 50%, and 90%, PRESTO, North America, 2013–2019.

^aSpline adjusted for age, race/ethnicity, education, BMI, smoking, physical activity, male partner education, last method of contraception, cycle length, intercourse frequency, history of sexually transmitted infection, doing something to improve chances of pregnancy, PSS score, MDI score, sleep duration, employment status, hours worked per week, and Healthy Eating Index score.