Pregnancy outcome and social conditions of women under 20: evolution in France from 1972 to 1981

Changes in risk factors of preterm delivery in France between 1981 and 1995

Because of the important changes in medical care and the social context of pregnancy, the relevance of well-established risk factors of preterm delivery (< 37 weeks) needs to be re-assessed. The objective of this study was to determine whether the associations between maternal characteristics and preterm delivery in France in 1995 were similar to those in 1981. We used two national representative samples of births, 5577 newborns in 1981 and 13318 in 1995. Univariable and multivariable analyses were applied to identify variables associated with increased risk of preterm delivery. Some risk factors were similar in 1981 and 1995, including age > 34 years and previous adverse obstetric history. Other factors that were observed in 1981 but which were not linked to preterm delivery in 1995 included the mothers being very young, single or foreign. However, parity and previous induced abortion were associated with preterm delivery in 1995, but not in 1981. These results show that the definition of high-risk groups used in prevention programmes should be brought up to date regularly.

Secular trends in the effect of socio-economic factors on birth weight and infant survival in Sweden

Time trends in the effect of socio-economic factors on low birth weight, stillbirth, perinatal deaths and deaths up to the age of one were studied using a medical birth registry linked to census information from 1975, 1980, and 1985. For each census year, delivery outcome the following year was studied. Two socio-economically different groups of women were studied, defined by occupation/education, cohabitation, and citizenship--one privileged and one under-privileged group. A difference in birth weight distribution was found between the two groups which is only partly explainable by different smoking habits in early pregnancy and did not substantially change during the ten year observation period. In 1976, there was virtually no difference in infant mortality between the two groups. In 1981 and 1986, infant mortality had decreased in both groups but more strongly so in the privileged group, and a difference between the groups therefore appeared.

Perinatal risk for infants of unmarried mothers over a period of 20 years

The perinatal events of the infants of 444 unmarried mothers, 3.7% of the total Northern Finland birth cohort from 1966, were compared with those of infants of 11,525 married mothers (95.5%), and a similar comparison was made between 395 (4.2%) unmarried mothers and 7516 (80.3%) married mothers in a second Northern Finland birth cohort in 1985-86. 1336 mothers, 14.3% of the mothers in this later cohort, were cohabiting. Divorced and widowed mothers were excluded from both cohorts. The infants of the unmarried mothers had a significantly lower mean birth weight, were more likely to be small for their gestational age (SGA), of low birth weight (LBW) (below 2500 g) and had a higher incidence of pre-term births than those of the married mothers in both cohorts. Perinatal mortality was significantly higher among the unmarried mothers only in the former cohort. These differences in perinatal events diminished markedly after adjustment for maternal age, parity, height, years of schooling and smoking habits, but did not totally disappear. The difference in the incidence of pre-term births diminished, but remained significant in both cohorts. The difference in mean birth weight, in the incidence of LBW infants and in perinatal mortality remained significantly less favourable to the unmarried mothers only in the 1966 cohort. It seems that the gap between the married and unmarried mothers had diminished. The incidence of SGA infants did not differ significantly between the married and unmarried mothers in either cohort after adjustment for the background variables. The cohabiting mothers formed an intermediate group between the married and single unmarried mothers in respect of perinatal events, but were close to the married mothers. In raw figures, the mean birth weight in this group was significantly lower and the incidence of SGA infants higher than among the married mothers, but these differences also disappeared after adjustment of the background variables.

Marital status and cohabitation during pregnancy: relationship with social conditions, antenatal care and pregnancy outcome in France

A survey of a representative sample of 5508 births in France in 1981 permitted the study of social characteristics of pregnant women, the medical care they received during their pregnancy and their pregnancy outcome, as a function of their marital status and whether or not they lived with the father of the child. Unmarried women living with the father (n = 412) like unmarried women living alone (n = 171), were more often younger, having their first baby and had a lower educational level than did married women living with the father (n = 4590). However, among the unmarried women, those living alone were in a more unfavourable position than those living with the father; in particular, they were more often less than 20 years old, had the minimum educational level required and were unemployed. Both groups of unmarried women had a higher preterm delivery rate than did married women, even after taking other risk factors into account in a logistic regression. The odds ratios (95% confidence interval) for pre-term delivery among unmarried mothers living without the father was 1.9 (1.0-3.4) and that for the unmarried cohabiting with the father was 1.6 (1.0-2.4). Thus, to fully appreciate the perinatal risks and medical needs during pregnancy, both the marital and cohabitational status of the women should be considered.