Effects of alcohol, cigarettes, methamphetamine and marijuana exposure during pregnancy on maternal serum alpha-fetoprotein levels at 20-24 weeks'gestation

Abstract

Objective: To examine the effects of cigarette, marihuana and methamphetamine smoking and consumption of alcohol during pregnancy on maternal serum alpha-fetoprotein (MSAFP) levels at 20-24 weeks.

Study design: In the Safe Passage Study (SPS) more than 12,000 pregnant women were prospectively followed up during pregnancy and until the infant was one year old to examine the effects of exposure to alcohol during pregnancy on stillbirth and sudden infant death syndrome. The present study is a cross-sectional secondary analysis of MSAFP analyses done at 20-24 weeks gestation in 1,679 SPS participants, recruited at the Bishop Lavis Community Health Centre, Cape Town, South Arica.

Results: Low or moderate alcohol consumption with or without smoking, nor methamphetamine or marihuana use affected mean MSAFP levels. High MSAFP levels were associated with high alcohol consumption, young age, low body mass index (BMI) (<18 kg/m²) or small mid upper arm circumference (MUAC) (<230mm). High MSAFP levels were associated with stillbirth, preterm birth, abruption and a birth weight z-score of less than -1.

Conclusion: The study confirms the association between high MSAFP levels and adverse pregnancy outcomes but, although exposure to smoking or drinking is associated with adverse pregnancy outcomes including stillbirth, MSAFP levels were not affected by any of these exposures except for continued high consumption of alcohol. The observed association between higher MSAFP levels and maternal nutritional status (as demonstrated by the lower MUAC and BMI) could explain some of the correlations of poor socioeconomic conditions with higher stillbirth rates effect.

Keywords: Z scores; alcohol; alpha-fetoprotein; birth weight; placental abruption; pregnancy; preterm birth; stillbirth; tobacco.

Figure 1

Study profile

Figure 2

Effect of alcohol trajectory on mean maternal serum alpha-fetoprotein values LS means current effect: F (4, 1738), 1.8834; p, 0.11 ; Kruskal-Wallis; p, 0.17 1, none; 2, moderate quit early; 3, high quit later; 4, low continuous; 5, high continuous.Vertical bars denote 95% confidence intervals.

Figure 3

Effect of mid upper arm circumference on mean maternal serum alpha-fetoprotein levels Weighted means current effect: F (2, 1701), 40.533; p<0.0001. Vertical bars denote 95% confidence intervals. Different letters above the vertical bars indicate significant differences, in this figure between all variables

Figure 4

Effect of BMI at recruitment on mean maternal serum alpha-fetoprotein levels Weighted means current effect: F (2, 1631), 42.714; p<0.0001. Vertical bars denote 95% confidence intervals. Different letters above the vertical bars indicate significant differences, e.g. in this figure between the first 2 variables (a) and last one (b) Difference between the first 2 variables is not significant as both have the same letter (a) above the vertical bars.

Figure 5

Association between Z-scores of birth weight and mean maternal serum alpha-fetoprotein levels Weighted means current effect: F (3, 1651), 13.363; p<0.0001. Vertical bars denote 95% confidence intervals. Different letters above the vertical bars indicate significant differences, e.g. in this figure between the first variables (a), the second two (b) and last one (c). Difference between the middle 2 variables is not significant as both have the same letter (b) above the vertical bars.