Table 2.
Association between periconceptionala antibiotic use and spontaneous abortion, by weeks of gestation, antibiotic type and indication for use
| No. of SABs | No. of pregnancies | Unadjusted HR (95% CI) |
Adjusted HRb (95% CI) |
|
|---|---|---|---|---|
| Periconceptional antibiotic use | ||||
| Yes | 121 | 585 | 1.06 (0.88, 1.28) | 1.06 (0.88, 1.28)c |
| No | 1416 | 7305 | 1.00 (Reference) | 1.00 (Reference) |
| Antibiotic use and gestational age | ||||
| <8 weeks gestation | ||||
| Yes | 81 | 540 | 1.05 (0.83, 1.32) | 1.03 (0.82, 1.30) |
| No | 955 | 6688 | 1.00 (Reference) | 1.00 (Reference) |
| 8–20 weeks gestation | ||||
| Yes | 40 | 467 | 1.10 (0.79, 1.53) | 1.11 (0.80, 1.54) |
| No | 461 | 5700 | 1.00 (Reference) | 1.00 (Reference) |
| Antibiotic type | ||||
| None | 1128 | 5599 | 1.00 (Reference) | 1.00 (Reference) |
| Penicillins | 28 | 148 | 0.93 (0.64, 1.36) | 0.95 (0.65, 1.39) |
| Nitrofurantoin | 15 | 66 | 1.17 (0.67, 2.03) | 1.14 (0.66, 1.96) |
| Cephalosporins | 14 | 49 | 1.43 (0.81, 2.52) | 1.37 (0.78, 2.42) |
| Macrolides | 10 | 41 | 1.22 (0.66, 2.27) | 1.16 (0.63, 2.17) |
| Antibiotic indication for use | ||||
| No antibiotic use | 1128 | 5599 | 1.00 (Reference) | 1.00 (Reference) |
| Urinary tract infection | 30 | 130 | 1.13 (0.75, 1.70) | 1.14 (0.77, 1.70) |
| Respiratory infection | 32 | 134 | 1.14 (0.80, 1.62) | 1.14 (0.79, 1.63) |
| Pelvic/vaginal infection | 16 | 71 | 1.19 (0.73, 1.94) | 1.15 (0.71, 1.89) |
a
Assessed on the questionnaire closest to conception
b
Adjusted for age, income, education, BMI, multivitamin use, parity, irregular menstrual cycles, doing something to improve chances of conception, intercourse frequency, history of SAB, alcohol intake closest to conception, smoking status closest to conception, pain medication closest to conception, history of pelvic inflammatory disease, history of chlamydia, last method of birth control, geographic region
c
Bias corrected estimate 1.34 (95% simulation interval 1.11–1.79)