Table 4.
Prepregnancy Folate Intake and Relative Risks of Spontaneous Abortion and Stillbirth Stratified by Gestational Length
| Categories of Intake (median, μg/day) | Fetal Loss < 8 Weeks | Fetal Loss 8–11 Weeks | Fetal Loss 12–19 Weeks | Fetal Loss 20+ Weeks | ||||
|---|---|---|---|---|---|---|---|---|
| Cases/Total | Multivariate-Adjusted RR (95% CI)* | Cases/Total | Multivariate-Adjusted RR (95% CI)* | Cases/Total | Multivariate-Adjusted RR (95% CI)* | Cases/Total | Multivariate-Adjusted RR (95% CI)* | |
| Total Folate | ||||||||
| Q1 (241) | 200/3185 | 1.00 (Ref) | 226/2886 | 1.00 (Ref) | 111/2596 | 1.00 (Ref) | 28/2467 | 1.00 (Ref) |
| Q2 (336) | 192/3192 | 0.92 (0.76, 1.11) | 250/2902 | 1.08 (0.91, 1.28) | 130/2594 | 1.10 (0.86, 1.41) | 25/2451 | 0.79 (0.46, 1.36) |
| Q3 (489) | 214/3197 | 1.00 (0.83, 1.21) | 224/2876 | 0.97 (0.81, 1.15) | 121/2603 | 1.00 (0.78, 1.29) | 26/2467 | 0.85 (0.50, 1.46) |
| Q4 (725) | 206/3186 | 0.95 (0.79, 1.15) | 245/2904 | 1.02 (0.86, 1.22) | 111/2621 | 0.90 (0.69, 1.16) | 23/2490 | 0.72 (0.41, 1.26) |
| Q5 (1161) | 189/3190 | 0.87 (0.72, 1.06) | 216/2941 | 0.88 (0.74, 1.06) | 121/2697 | 0.95 (0.74, 1.23) | 18/2568 | 0.55 (0.30, 1.00) |
| P for Trend | 0.22 | 0.08 | 0.31 | 0.06 | ||||
| Folate from Supplements | ||||||||
| Q1 (0) | 408/6638 | 1.00 (Ref) | 489/6030 | 1.00 (Ref) | 248/5416 | 1.00 (Ref) | 53/5134 | 1.00 (Ref) |
| Q2 (228) | 261/3779 | 0.96 (0.82, 1.12) | 292/3391 | 0.92 (0.80, 1.07) | 148/3048 | 0.96 (0.78, 1.18) | 31/2885 | 0.92 (0.58, 1.45) |
| Q3 (400) | 218/3351 | 0.97 (0.82, 1.14) | 245/3047 | 0.92 (0.79, 1.07) | 126/2756 | 0.93 (0.76, 1.15) | 23/2609 | 0.79 (0.48, 1.29) |
| Q4 (1000) | 114/2182 | 0.79 (0.64, 0.97) | 135/2041 | 0.76 (0.63, 0.92) | 72/1891 | 0.78 (0.60, 1.01) | 13/1815 | 0.66 (0.36, 1.21) |
| P for Trend | 0.03 | 0.005 | 0.05 | 0.14 | ||||
RR, relative risk; CI, confidence interval.
*
Adjusted for age (continuous), energy intake (continuous), body mass index (<18.5, 18.5–24.9, 25–29.9, ≥30, and missing), smoking status (never, former, current, and missing), physical activity (< 3 MET-h/wk, 3–8.9 MET-h/wk, 9–17.9 MET-h/wk, 18–26.9 MET-h/wk, 27–41.9 MET-h/wk, >42 MET-h/wk, and missing), year of pregnancy (continuous), history of infertility (no, yes, and missing), and marital status (married, not married), and race (white, other).