[Distribution of birth weights between 2011 and 2015 and changes in percentile figures between 1996 and 2015. Analyis...

Introduction and aim: We aimed to provide a current birth weight percentile table for singleton and twin pregnancies stratified by gestational week at delivery and sex using data from all live births in Hungary between 2011 and 2015. In addition, we examined temporal trends in average birth weights in singleton and twin pregnancies by sex in five-year periods between 1996 and 2015. Method: We calculated the 5th, 10th, 25th, 50th, 75th, 90th, and 95th centiles of birth weight for each gestational week by sex for singleton and twin pregnancies using compulsory collected obstetrical data (Tauffer Statistics) in Hungary in 2011-2015. Furthermore, we described changes in birth weights by gestational week between 5-year periods from 1996 to 2015. Results: We present birth weight centiles for live births in both tabular and graphical forms using data from 2011 to 2015. In general, live birth weights in gestational weeks 35-41 were lower in the period of 1996-2005 (the lowest in 1996-2000) and were higher in the period of 2006-2010 compared to the reference period of 2011-2015 (e.g., the average male newborn weighed 3249 g at gestational week 38 in 2011-2015, which is 34.3 [SE at 3.0] g less in 1996-2000, 11.5 [2.9] g less in 2001-2005, and 18.1 [2.9] g more in 2006-2010). Similar trends were not observed in birth weights of twin pregnancies in gestational weeks 35-38. Conclusion: Given the observed substantial change in birth weights during the past 20 years, renewal of the commonly used percentile tables is necessary. Birth weights increased from 1996 to 2010, mainly of mature newborns, followed by a stabilization or slight decrease in the later periods. Orv Hetil. 2019; 160(36): 1426-1436.