The duration of pregnancy and the arrival of childbirth is not an exact calculation, but is subject to a variability of up to five weeks. This has been determined by a study published in the specialized journal Human Reproduction. Until now, it was considered as the probable date of birth 280 days a
The duration of pregnancy and the arrival of childbirth is not an exact calculation, but is subject to a variability of up to five weeks. This has been determined by a study published in the specialized journal Human Reproduction.
Until now, it was considered as the probable date of birth 280 days after the start of the last menstruation, but according to figures published by Europa Press, only 4 percent of pregnant women gave birth after that date. For this reason, researchers linked to the US National Institutes of Health han have sought to determine the exact moment in which the woman ovulates and the subsequent implantation of the embryo in the uterus.Ovulation and implantation of the embryoFollowing this methodology, they were able to calculate the total gestation period of 125 pregnancies that included a variability of
up to 37 days
on completion. "We found that the average time from ovulation to birth was 268 days, that is, 38 weeks and two days," says Dr. Anne Marie Jukic, a postdoctoral fellow at the Epidemiology Service of the National Institute of Environmental Health , in Durham (USA). The female hormones, key in the investigation
This study was carried out thanks to the analysis of urine samplesdaily of 125 women who had taken part in a previous investigation. In these analyzes were calculated the concentrations of three hormones related to the onset of pregnancy, hCG (human chorionic gonadotropin), estrone-3-glucuronide and pregnandiol-3-glucuronide.
Researchers set the exact day of ovulation when there was a decrease in the ratio between
estrogen and progestogen, while embryo implantation was identified thanks to the increase in hCG levels. Other factors that influence the date of delivery
The research also shows other factors that influence on the date of birth of the baby. Thus, if the embryo took longer to implant, it also took longer to complete the pregnancy. The same happens when the mother's age is higher and the greater her birth weight was.
On the contrary, those pregnancies that showed an increase in progesterone levels in the last weeks were significantly shorter, with an average of
12 days of gestation less. The authors of the study conclude that the events prior to the confirmation of pregnancy influence the date of arrival of the baby and can determine new lines of research on childbirth. Sources: