Table 2.
Pre-pregnancy healthy lifestyle factors and risk of adverse pregnancy outcomes throughout pregnancy and after 20 weeks’ gestation, the Nurses’ Health Study II (NHSII), 1991–2009
| Healthy lifestyle | All pregnancies* (27135 pregnancies from 15509 women) |
Pregnancies ≥20 gestational weeks† (21516 pregnancies from 14284 women) |
||||
|---|---|---|---|---|---|---|
| Cases/ Total pregnancies |
Model 1, multivariable adjusted |
Model 2, with additional mutual adjustment |
Cases/ Total pregnancies |
Model 1, multivariable adjusted |
Model 2, with additional mutual adjustment |
|
| RR (95% CI) | RR (95% CI) | |||||
| Body mass index, kg/m2 | ||||||
| <18.5 | 307/1052 | 0.92 (0.84–1.02) | 0.93 (0.85–1.03) | 120/862 | 0.86 (0.72–1.02) | 0.86 (0.73–1.02) |
| 18.5–24.9 | 6336/19134 | 1.0 [reference] | 1.0 [reference] | 2626/15349 | 1.0 [reference] | 1.0 [reference] |
| 25–29.9 | 1994/4778 | 1.23 (1.18–1.28) | 1.22 (1.17–1.27) | 912/3678 | 1.44 (1.34–1.54) | 1.42 (1.32–1.52) |
| 30–34.9 | 676/1450 | 1.36 (1.28–1.45) | 1.34 (1.26–1.42) | 337/1109 | 1.74 (1.57–1.92) | 1.68 (1.52–1.86) |
| ≥35 | 389/721 | 1.49 (1.39–1.61) | 1.46 (1.35–1.58) | 188/518 | 2.03 (1.79–2.29) | 1.92 (1.69–2.18) |
| P trend | <0.001 | <0.001 | <0.001 | <0.001 | ||
| Smoking | ||||||
| Never | 6875/19668 | 1.0 [reference] | 1.0 [reference] | 3001/15722 | 1.0 [reference] | 1.0 [reference] |
| Past | 2037/5558 | 1.00 (0.96–1.04) | 0.99 (0.95–1.04) | 825/4328 | 0.97 (0.90–1.05) | 0.98 (0.91–1.06) |
| Current | 790/1909 | 1.16 (1.09–1.23) | 1.11 (1.05–1.18) | 357/1466 | 1.20 (1.08–1.33) | 1.15 (1.04–1.28) |
| P trend | <0.001 | 0.01 | 0.02 | 0.04 | ||
| Moderate and vigorous physical activity, min/week | ||||||
| 0–29.9 | 3159/8755 | 1.0 [reference] | 1.0 [reference] | 1395/6952 | 1.0 [reference] | 1.0 [reference] |
| 30–89.9 | 2101/5845 | 1.00 (0.95–1.05) | 1.02 (0.98–1.07) | 903/4623 | 0.96 (0.89–1.04) | 1.00 (0.92–1.08) |
| 90–149.9 | 691/1906 | 1.00 (0.94–1.07) | 1.05 (0.98–1.12) | 302/1510 | 0.97 (0.87–1.09) | 1.05 (0.94–1.17) |
| 150–299.9 | 1868/5262 | 0.97 (0.92–1.02) | 1.02 (0.97–1.07) | 781/4163 | 0.89 (0.82–0.97) | 0.97 (0.90–1.06) |
| ≥300 | 1883/5367 | 0.94 (0.90–0.99) | 1.01 (0.96–1.06) | 802/4268 | 0.87 (0.81–0.95) | 0.98 (0.90–1.07) |
| P trend | 0.008 | 0.66 | <0.001 | 0.51 | ||
| Diet (DASH) | ||||||
| Q1 | 2359/6173 | 1.0 [reference] | 1.0 [reference] | 1080/4877 | 1.0 [reference] | 1.0 [reference] |
| Q2 | 2007/5573 | 0.92 (0.88–0.97) | 0.95 (0.90–0.99) | 865/4413 | 0.88 (0.81–0.95) | 0.91 (0.84–0.99) |
| Q3 | 1379/3996 | 0.88 (0.84–0.93) | 0.91 (0.86–0.97) | 611/3214 | 0.85 (0.78–0.93) | 0.89 (0.81–0.97) |
| Q4 | 1939/5570 | 0.88 (0.84–0.93) | 0.93 (0.88–0.97) | 813/4422 | 0.81 (0.75–0.89) | 0.87 (0.79–0.94) |
| Q5 | 2018/5823 | 0.86 (0.82–0.90) | 0.91 (0.86–0.96) | 814/4590 | 0.78 (0.72–0.85) | 0.85 (0.78–0.93) |
| P trend | <0.001 | <0.001 | <0.001 | <0.001 | ||
| Alcohol consumption, g/day | ||||||
| 0 | 3920/11253 | 1.0 [reference] | 1.0 [reference] | 1801/9095 | 1.0 [reference] | 1.0 [reference] |
| 0.1-4.9 | 3909/10817 | 1.00 (0.97–1.04) | 1.01 (0.97–1.05) | 1643/8498 | 0.93 (0.87–0.99) | 0.96 (0.90–1.02) |
| 5.0-14.9 | 1580/4292 | 0.97 (0.93–1.02) | 0.99 (0.94–1.04) | 629/3335 | 0.86 (0.79–0.94) | 0.92 (0.84–1.00) |
| 15.0-29.9 | 231/594 | 0.97 (0.87–1.08) | 0.98 (0.88–1.10) | 85/447 | 0.82 (0.67–1.00) | 0.87 (0.71–1.06) |
| ≥30 | 62/179 | 0.87 (0.70–1.08) | 0.83 (0.67–1.04) | 25/141 | 0.79 (0.55–1.12) | 0.77 (0.54–1.10) |
| P trend | 0.19 | 0.35 | <0.001 | 0.007 | ||
| Multivitamin use, times/week‡ | ||||||
| 0 | 3733/9992 | 1.0 [reference] | 1.0 [reference] | 1523/7749 | 1.0 [reference] | 1.0 [reference] |
| 1-2 | 719/1869 | 0.97 (0.91–1.03) | 0.99 (0.93–1.05) | 291/1433 | 0.98 (0.88–1.09) | 1.02 (0.91–1.14) |
| 3-5 | 1451/4003 | 0.94 (0.89–0.99) | 0.96 (0.91–1.00) | 590/3123 | 0.96 (0.88–1.04) | 0.99 (0.91–1.07) |
| ≥6 | 3760/11161 | 0.86 (0.83–0.89) | 0.88 (0.85–0.91) | 1758/9119 | 0.93 (0.88–0.99) | 0.97 (0.92–1.03) |
| P trend | <0.001 | <0.001 | 0.02 | 0.29 | ||
DASH, Dietary Approaches to Stop Hypertension (higher score indicates healthier diet). Q, quintile.
Adverse pregnancy outcomes included miscarriage, ectopic pregnancy, gestational diabetes, hypertensive disorders of pregnancy (gestational hypertension and preeclampsia), preterm birth, stillbirth, and low birthweight.
Adverse pregnancy outcomes included gestational diabetes, hypertensive disorders of pregnancy (gestational hypertension and preeclampsia), preterm birth, stillbirth, and low birthweight.
96 participants reported use of multivitamin but did not report frequency of multivitamin use were excluded from this analysis.
Multivariable log-Poisson regression models with generalized estimating equations were used to estimate RRs and 95% CIs. Model 1: adjusted for age, race and ethnicity, year of birth, history of infertility, parity, and interpregnancy interval. Model 2: Model 1 + mutual adjustment for other healthy lifestyle factors in the table.
P trend tests were conducted treating indicator levels as continuous variables.