Family status and low birth weight risk: trends and changes over time

Jitka Rychtarikova, Charles University in Prague

The frequency of children born with low birth weight (less than 2 500 grams) has recently increased in the Czech Republic. In 2010, 8.2 % live births with low birth weight were reported, compared to only 5.7 % in 1986. Over the same time period, the percentage of extramarital live births increased from 7.4 % to 40.3 %. Unmarried mothers are often considered to be more likely to deliver a low-birth weight baby. However, the adverse effect on low birth weight outcome can also vary according to age, education and other factors. In addition, the increasing size of the population of unmarried mothers is becoming more heterogeneous today than in the past when they represented a small marginal group. The proposed research focuses on examining changes in low birth weight over time (1986-2010) across three groups of live births: children born to unmarried women, those coming from premarital conceptions, and children conceived after marriage. The analysis also allows us to compare the impact of two different socio-economic settings (before and after 1989) on birth weight. The aim is primarily to disentangle the effect of changing structure of mothers from the effects of intensity change. In the first stage, the trends in low birth weight by three family statuses (extramarital, premarital, and marital) for the years 1986-2010 will be compared based on several risk factors changing over time (multiplicity, maternal age, birth order, and educational attainment). Next, logistic regression will be used to estimate the unadjusted and adjusted odds ratios of risk factors for low birth weight (dependent variable). The data are individual anonymous records of vital statistics (2 735 238 live births) collected by the Czech Statistical Office for the period 1986-2010.