The risks of a range of maternal pregnancy choices, expressed as "baby micromorts" (risk of death per million births).

OBJECTIVE: To present the risks of baby death from various maternal choices on a common scale. DESIGN: Review of published data. METHODS: Mortality calculated as the attributable risk per activity, expressed in "baby micromorts", the number of one in a million chances of the baby dying. RESULTS: Amniocentesis and chorionic villous sampling carry procedure related risks of 9142 (-600 to 19,000) and 37,902 (23,302 to 52,502) micromorts respectively. Smoking carries a risk of 0.21 micromorts per cigarette or 300 micromorts for a woman smoking 5/day throughout pregnancy. Drinking a unit of alcohol in the first trimester carries a risk of 400 micromorts via miscarriage or 19,200 micromorts for a woman drinking 4 units/week in the first trimester. The risk per unit due to stillbirth is only about 19 or 3,710 micromorts when drinking 5 units/week throughout pregnancy. Cocaine use carries a risk of about 45 micromorts per single use; 3,630 micromorts using cocaine twice/week during pregnancy. For low risk women in the UK, planned first birth at home carries an additional 843 (-200 to 2620) micromorts compared with in hospital, and planned vaginal breech birth an additional 5870 (-4400 to 18,500), compared with planned caesarean. The risk of delaying conception by a year varies by age group. For women aged 35-39 the risk increases by 220 (-430 to 870) micromorts each year versus 600 (-800 to 2000) micromorts for women aged over 40. Compared with the above, the risk from the mother eating a serving of unpasteurised cheese, is negligible at 0.00026 micromorts. CONCLUSIONS: This way of expressing risk may help put choices which pregnant women make into perspective, although it needs evaluating in well conducted experimental studies.

Comparison of nicotine exposure during pregnancy when smoking and abstinent with nicotine replacement therapy: systematic review and meta-analysis.

BACKGROUND AND AIMS: Smoking during pregnancy is strongly associated with negative pregnancy and perinatal outcomes. Some guidelines recommend nicotine replacement therapy (NRT) for smoking cessation during pregnancy, but adherence with NRT is generally poor and could be partially explained by nicotine-related safety concerns. We compared pregnant women's cotinine and nicotine exposures from smoking with those when they were abstinent from smoking and using NRT. DESIGN: Systematic review with meta-analysis and narrative reporting. Twelve studies were included: in most, only one type of NRT was used. Seven were quality-assessed and judge of variable quality. SETTING: Studies from any setting that reported nicotine or cotinine levels when smoking and later when abstinent and using NRT. PARTICIPANTS: Pregnant women who smoked and became abstinent but used NRT either in a cessation study or in a study investigating other impacts of NRT. MEASUREMENTS: We quality-assessed longitudinal cohort studies using a modified version of the Newcastle-Ottawa scale. For meta-analysis, we used mean within-person differences in cotinine or nicotine levels when smoking and at later follow-up when abstinent and using NRT. Where such data were not available, we calculated differences in group mean levels and reported these narratively, indicating where data were not completely longitudinal. FINDINGS: Of the 12 included studies, four cotinine-measuring studies (n = 83) were combined in a random effects meta-analysis; the pooled estimate for the mean difference (95% confidence intervals) in cotinine levels between when women were smoking and abstinent but using NRT was 75.3 (57.1 to 93.4) ng/ml (I2  = 42.1%, P = 0.11). Of eight narratively-described studies, six reported lower cotinine and/or nicotine levels when abstinent and using NRT; two had mixed findings, with higher levels when abstinent but using NRT reported from at least one assay time-point. CONCLUSIONS: Pregnant women who use nicotine replacement therapy instead of smoking reduce their nicotine exposure.