| Abstract [eng] |
Introduction. Gestational age (GA) – defined as the period from the first day of the last menstrual period to the moment of birth – is an important indicator of newborn health. Studies show that over the past decades, the distribution of gestational age at birth has undergone significant changes in many countries. Many nations have recorded a trend toward births occurring earlier than the 40th week of pregnancy, while the proportion of late-term (41–42 weeks) and post-term (>42 weeks) deliveries has declined. Aim of the research. To evaluate the changes in gestational age of singleton, live-born, naturally delivered, full-term newborns in Lithuania during the study period. Materials and methods. Medical birth data from 1995 to 2022 were used in the analysis. All live singleton births between 37 and 43 weeks of gestation, delivered vaginally without induction or augmentation of labor, were included. The final analytical sample comprised 548,144 births. Statistical analyses were performed using IBM SPSS Statistics software (version 30.0). Results. During the study period, the mean gestational age of spontaneously delivered singleton, term newborns decreased from 39.71 weeks in 1995 to 39.38 weeks in 2022, a reduction of 0.33 weeks (2.31 days). Significant shifts were observed in the maternal age distribution: in 1995, the largest proportion of births was among women aged 20–24 years (38.6%), but by 2022 this share had decreased to 11.3%. Meanwhile, the proportion of women aged 30–34 increased from 15.0% to 36.6%, becoming the largest age group among mothers. The most substantial and statistically significant reductions in GA were observed among mothers aged 18–19 years (0.43 weeks) and 35–39 years (0.39 weeks). Among fourth and subsequent births, the largest decrease in mean GA was recorded for both newborn sex subgroups: for boys, GA declined from 39.75 weeks (1995) to 39.19 weeks (2022), and for girls – from 39.70 to 39.23 weeks, corresponding to reductions of 0.56 and 0.47 weeks, respectively. In all years of the study period, the mean gestational age of newborns from two-parent families was consistently higher than that of those from single-parent families, with statistically significant differences observed in 1995–2010, 2012, and 2017–2018. Maternal education was associated with gestational age: the longest average GA was recorded among mothers with college-level education (39.62 weeks), whereas the shortest was observed in mothers with only primary or lower secondary education (39.49 weeks). Between 2016 and 2022, the mean gestational age of newborns born to healthy mothers was significantly higher than that of mothers with health conditions (p<0.001). During the study period, the birth length and weight of boys and girls born at 37–41 weeks of gestation increased significantly (p<0.001), while head circumference remained relatively unchanged. Conclusions. From 1995 to 2022, the average gestational age of spontaneously delivered, term singleton newborns decreased by 0.33 weeks. This decline was primarily driven by an increase in the proportion of births occurring at 37–39 weeks of gestation and a decrease in births at 40 weeks or later. During the study period, the proportion of older mothers increased. Newborns born into two-parent families and to healthy mothers had longer gestational ages. Mothers with college-level education experienced the longest pregnancy durations. Throughout the period, newborn birth weight and length increased, while head circumference did not show statistically significant changes. Keywords: gestational age; marital status; maternal age; maternal education; newborn physical characteristics; parity. |
