Table 2.
Relative risk of diet and lifestyle behaviours according to pregnancy intention in the ALSWH and SWS cohorts1
| ALSWH Cohort2 | SWS Cohort3 | ||||||
|---|---|---|---|---|---|---|---|
| Risk factors | Using contraception or no male sexual partner N=6256 (77%) |
Trying for pregnancy N=536 (7%) |
Not using contraception N=1285 (15.9%) |
Not planning pregnancy and not pregnant N=9932 (80%) |
Unintended pregnancy N=301 (2%) |
Intended pregnancy N=584 (5%) |
Planning a pregnancy but not pregnant N=1623 (13%) |
| Smoking (yes vs no) | 1.00 | 0.84 (0.76, 0.93) | 1.09 (1.01, 1.18) | 1.00 | 1.15 (1.00, 1.33) | 0.72 (0.61, 0.83) | 0.89 (0.82, 0.96) |
| Alcohol consumption (yes vs no) | 1.00 | 0.70 (0.56, 0.87) | 0.91 (0.77, 1.09) | 1.00 | 1.01 (0.98, 1.05) | 1.03 (1.01, 1.06) | 0.99 (0.97, 1.00) |
| Fruit and vegetable consumption (<5 vs ≥5 serves per day) | 1.00 | 1.01 (0.99, 1.03) | 0.97 (0.96, 0.99) | 1.00 | 1.05 (0.94, 1.17) | 0.94 (0.85, 1.03) | 0.97 (0.92, 1.03) |
| Physical activity (<30 vs ≥30 minutes per day) | 1.00 | 1.06 (1.01, 1.11) | 1.14 (1.09, 1.18) | ||||
| Body mass index (≥25 vs <25 kg/m2) | 1.00 | 1.05 (1.00, 1.10) | 1.16 (1.12, 1.21) | 1.00 | 0.98 (0.85, 1.13) | 1.10 (1.00, 1.21) | 1.13 (1.07, 1.20) |
| Caffeine consumption (>300mg caffeine per day) | 1.00 | 1.15 (1.01, 1.31) | 0.89 (0.79, 0.99) | 0.94 (0.88, 1.01) | |||
All analyses are relative risks and 95% confidence intervals estimated using Poisson regression with robust variance, adjusted for maternal age, level of educational attainment and parity. Statistically significant results (P < 0.05) are highlighted in bold.
The Australian Longitudinal Study on Women’s Health (ALSWH) is a population-based study of women born in 1973-78 who have been surveyed every 3-4 years since 1996 (age 18-23 years) [5]. ALSWH women who indicated they or their partner cannot have children were excluded from analysis. N was taken from Survey 3, which was the first survey where women were asked about pregnancy intention.
The Southampton Women’s Survey (SWS) recruited 12,583 non-pregnant women aged 20-34 years between 1998 and 2002 [6, 7]. When not pregnant, SWS women were asked whether they anticipated trying for a baby within the following year. Data about pregnancy within a year were then used to define four groups of women: not planning pregnancy and not pregnant, unintended pregnancy, intended pregnancy, and planning a pregnancy but not pregnant.