Study #3: Maternal cigarette, alcohol, and coffee consumption in relation to risk of clubfoot. Werler M et al., Paediatr Perinat Epidemiol 2015 Jan;29(1):3-10.

Abstract: A team of investigators assessed maternal alcohol and coffee drinking in relation to clubfoot, a common congenital (present at birth) foot deformity. The study was conducted in a large Northeastern US hospital from 2007 to 2011. A total of 646 infants born with clubfoot and a sample of 2,037 age- and geography-matched infants without clubfoot were identified from hospital neonatal records. Their mothers were contacted and interviewed by research staff about pregnancy events and exposures, including the timing and frequency of cigarette smoking, alcohol intake, and coffee drinking. More mothers of babies with clubfoot than without reported smoking during early pregnancy (28.9% vs. 19.1%). Of women who smoked when they became pregnant, those who quit in the month after a first missed period had a 40% increase in clubfoot risk and those who continued to smoke during the next 3 months had more than a doubling in risk, after controlling for demographic factors, parity, obesity, and specific medication exposures. Adjusted measures of association for women who drank >3 servings of alcohol or coffee per day throughout early pregnancy were 2.38 and 1.77, respectively. The findings suggest that clubfoot risk appears to be increased for offspring of women who smoke cigarettes, particularly those who continue smoking after pregnancy is recognizable, regardless of amount. For alcohol and coffee drinkers, suggested increased risks were only observed in higher levels of intake.

Question A: What type of study design was this?

Question B: List two advantages and two disadvantages of this type of study design.

Advantages:

Disadvantages:

Question C: What was the exposure(s) of interest? How was it measured?

Question D: Which relative measure of association is most appropriate for this type of study design? Why is it most appropriate?