Table 1.
Baseline characteristics by periconceptional antibiotic use, Pregnancy Study Online, 2013–2021
| Characteristica | Antibiotic Use | |
|---|---|---|
| Non-use | Use | |
| Number of participants (%) | 7,293 (92%) | 585 (7%) |
| Age (years, mean) | 30.1 | 30.1 |
| Partner’s age (years, mean) | 31.8 | 32.2 |
| White, non-Hispanic (%) | 85.9 | 84.6 |
| Annual household income, USD (%) | ||
| <$50,000 | 13.8 | 18.7 |
| $50,000-$99,000 | 35.5 | 36.9 |
| $100,000-$149,000 | 27.7 | 25.0 |
| ≥$150,000 | 20.3 | 16.6 |
| Education (%) | ||
| High school or less | 3.0 | 5.1 |
| Some college | 17.0 | 19.8 |
| College | 34.7 | 34.8 |
| Graduate school | 45.3 | 40.3 |
| Geographic Region (%) | ||
| Midwest | 21.8 | 23.5 |
| Northeast | 24.3 | 20.7 |
| South | 22.1 | 25.2 |
| West | 16.0 | 17.6 |
| Canada | 15.8 | 13.4 |
| BMI (kg/m2, mean) | 26.8 | 27.5 |
| Parous (%) | 32.9 | 33.9 |
| Irregular menstrual cycles (%) | 13.4 | 17.0 |
| Doing something to improve chances of conceiving (%) | 81.0 | 81.3 |
| Intercourse Frequency (%) | ||
| <1 time per week | 20.0 | 19.2 |
| ≥4 times per week | 14.8 | 20.1 |
| Hormonal last method of contraception (%) | 36.0 | 40.5 |
| History of spontaneous abortion (%) | 25.0 | 31.6 |
| History of infertility (%) | 7.6 | 11.9 |
| History of chlamydia (%) | 7.1 | 8.0 |
| Physical activity (MET-hrs/wk, mean)b | 35.5 | 33.5 |
| Multivitamin use (%)b | 85.7 | 82.4 |
| Smoking Status (%)b | ||
| Never | 80.8 | 74.9 |
| Former | 12.6 | 14.9 |
| Current Occasional | 2.7 | 3.2 |
| Current Regular | 4.0 | 7.0 |
| Alcohol intake (drinks/week, mean)b | 3.1 | 2.6 |
| Caffeine intake (mg/day, mean)b | 121.3 | 119.8 |
| Pain medication use (%)b | 67.6 | 76.7 |
| Perceived stress score (mean)b | 15.9 | 16.3 |
Abbreviations: USD = United States Dollar. Notes: Conception defined as 14 days after date of last menstrual period.
a
All characteristics except for age are standardized to the age distribution of cohort at baseline.
b
Assessed at follow-up closest to conception