How effective are smoking cessation and nutritional interventions in preventing low birth weight?

The issue

Low birth weight is a major cause of infant mortality and morbidity around the world. It is defined by the World Health Organization as a birth weight less than 2500 grams, since below that threshold, infant mortality begins to rise rapidly. Low birth weight is caused by a short gestation, retarded intrauterine growth or a combination of both.


Interventions to stop smoking are effective among pregnant women when provided by trained personnel using pregnancy-specific materials as part of antenatal care. There is evidence that effective smoking cessation interventions reduce the prevalence of low birth weights and increase birth weights among pregnant women who quit. Lower-quality evidence suggests that reducing the number of cigarettes smoked has health benefits too. However, little is known about the particular components of such interventions that affect outcomes. There is insufficient evidence to draw conclusions about the potential benefit or harm of nicotine replacement therapy for pregnant women. High relapse rates are known among pregnant women who quit smoking. There is consensus that the transition from pregnancy to the postpartum period is a critical stage in not starting to smoke again.

Among nutritional interventions, there is evidence that calcium supplementation reduces premature birth rates and the incidence of low birth weight, especially in women at risk for hypertensive disorders. There is low-quality evidence on the effectiveness of balanced protein/energy supplementation in preventing intrauterine growth retardation and small-for-gestational age births, but other low-quality evidence suggests that such supplementation is ineffective in preventing premature births. For other interventions – including magnesium supplementation, isocaloric balanced protein supplementation, high-protein supplementation, nutritional advice, combined iron and folate supplementation, iron supplementation, vitamin D supplementation, fish oil supplementation, and atypical maternal supplementation – the available evidence is low quality, insufficient, conflicting, or lacking.

Policy considerations

The widespread use of unproven and ineffective supplements in pregnancy suggests the need for action by health care insurers and those developing clinical guidelines. Promoting or requiring smoking cessation interventions, especially in areas with high rates of smoking, could result in substantial health benefits.

The views expressed in this summary are based on a publication of a HEN Network member agency and do not necessarily represent the decisions or stated policy of WHO/Europe.