Strange linearities in human pregnancy. The immediate immense consequences for personal women’s reproductive lives

Abstract

Maternal ages categories (by 5 years of age, 15-19, 20-24, 25-29 etc.) as well as pre-pregnancy body mass index (BMI), also interestingly by categories of 5 kg/m² (15-19 kg/m², 20-24 etc..) have both linear associations with important maternal/fetal morbidities. For maternal ages: rate of cesarean sections, vaginal deliveries, active vaginal procedures (vacuum, forceps etc.), incidence of breech presentation at term, placenta praevia. For pre-pregnancy BMI, allowing to define optimal gestational weight gain (GWG) for the index pregnancy: : rate of cesarean sections, vaginal deliveries, rates of large or small for gestational ages newborns (LGA&SGA), rate of macrosomic babies (≥ 4 kg), and incidence of late-onset preeclampsia (≥ 34 weeks gestation, 80 to 90% of preeclampsia cases in a population). Conclusion:These linear associations (biological mathematical laws?) suggest underlying biological principles to investigate. It implies immediate practical consequences: First, prediction since the beginning of any pregnancy of important maternal/fetal morbidities. Second, by calculating optimal gestational weight gain, should permit to lower these important complications. Third, because of these linearities maternal ages as well as pre-pregnancy BMI divided by increments of 5 (or as continuous variable) should be in the future included in quite all logistical models in epidemiological perinatal studies.