Table 6.
Unadjusted risk ratios for variables associated with subsequent uncomplicated pregnancy remaining significant in log probability regression model
| Variables | Risk ratio (95% CI) | ||
|---|---|---|---|
| Development dataset (n=2129) | Local replication dataset (n=1063) | External confirmation dataset (n=2432) | |
| Potentially improvable | |||
| Decreased risk of uncomplicated pregnancy/detrimental: | |||
| Body mass index at 15 weeks’ gestation: | |||
| ≥30 (v <25) | 0.71 (0.63 to 0.79) | 0.66 (0.56 to 0.78) | 0.74 (0.65 to 0.84) |
| 25-29.9 (v <25) | 0.90 (0.83 to 0.97) | 0.86 (0.77 to 0.96) | 0.87 (0.80 to 0.94) |
| Mean blood pressure (per 5 mmHg increase) at 15 weeks’ gestation: | |||
| Diastolic | 0.93 (0.91 to 0.94) | 0.93 (0.91 to 0.96) | 0.92 (0.91 to 0.94) |
| Systolic | 0.94 (0.93 to 0.96) | 0.94 (0.93 to 0.95) | 0.95 (0.94 to 0.96) |
| Misuse of drugs in first trimester* | 0.86 (0.78 to 0.96) | 0.93 (0.81 to 1.07) | 0.90 (0.84 to 0.97) |
| Increased risk of uncomplicated pregnancy/ beneficial: | |||
| Prepregnancy fruit intake at least 3 times/day | 1.19 (1.11 to 1.27) | 1.25 (1.14 to 1.36) | 1.09 (1.01 to 1.18) |
| Hours worked in paid employment (per 8 hours increase) at 15 weeks’ gestation | 1.03 (1.01 to 1.04) | 1.02 (1.00 to 1.04) | 1.02 (1.01 to 1.04) |
| Non-modifiable | |||
| Decreased risk of uncomplicated pregnancy/detrimental: | |||
| Maternal socioeconomic index at 15 weeks’ gestation: | |||
| 1st (bottom) fifth (v 5th (top) fifth): | 0.84 (0.75 to 0.93) | 0.95 (0.81 to 1.11) | 0.83 (0.74 to 0.92) |
| 2nd fifth (v top fifth) | 0.86 (0.77 to 0.96) | 0.91 (0.77 to 1.07) | 0.88 (0.80 to 0.98) |
| 3rd fifth (v top fifth) | 0.97 (0.88 to 1.06) | 1.07 (0.92 to 1.23) | 0.88 (0.79 to 0.97) |
| 4th fifth (v top fifth) | 1.02 (0.93 to 1.12) | 1.06 (0.92 to 1.23) | 0.93 (0.85 to 1.03) |
| Hypertension with oral contraceptive pill use before pregnancy | 0.59 (0.39 to 0.90) | 0.58 (0.32 to 1.04) | 0.47 (0.26 to 0.85) |
| Family history of any hypertensive disorder in pregnancy | 0.87 (0.80 to 0.96) | 0.84 (0.74 to 0.96) | 0.87 (0.79 to 0.97) |
| Vaginal bleeding (more than spotting) in pregnancy before 15 weeks’ gestation | 0.88 (0.81 to 0.96) | 0.88 (0.78 to 0.99) | 0.88 (0.81 to 0.96) |
| Mean uterine artery resistance index (per 0.1 increase) at 20 weeks’ gestation | 0.91 (0.88 to 0.94) | 0.91 (0.87 to 0.95) | 0.95 (0.92 to 0.98) |
*Use of marijuana, cocaine/crack, amphetamines, 3,4 methylenedioxymethamphetamine, opiates, hallucinogens, and binge alcohol ≥6 units/session.