Pregnancy is the period between the fertilization of an egg and the birth of the newborn. In the human race this period is about nine months.
Pregnancies are dated from the first day of the last menstrual period and the probable date of delivery is calculated 40 weeks later. According to these accounts, an initial period is included in this calculation , which in women with regular cycles is two weeks , in which the woman is not yet pregnant, but usually the date of the last menstruation is the only data available for date gestation. In cases where we know the date of conception, it would be a matter of adding 38 weeks to that date.
Phases of pregnancy
We also divide pregnancy into trimesters , because each of them has its different connotations:
- The first trimester , the first three months or counting in weeks from conception to week 13-14 , is the one with the highest risk of pregnancy losses, spontaneous abortions that are frequent in this trimester as they are pregnancies resulting from embryos with some defect chromosomal or anatomical that does not allow it to continue developing normally beyond the first few weeks. It is the period in which all the fetal organs will form , which will be complete at the end of this trimester. We also associate this period of pregnancy with the most uncomfortable for the pregnant woman, since it is during these early stages that nausea and vomiting of pregnancy manifest.
- Second trimester is the central, transitional period, from 13-14 to 26-28 weeks , during which the fetus basically grows and gains weight , the formation of all its organs is completed during the first trimester, the mother is She finds the initial symptoms better and she still does not show the discomfort of the end of pregnancy.
- The third trimester are the last weeks, in which the fetus has already acquired a considerable weight and volume responsible for the discomfort that pregnant women report due to carrying that weight with them. During this period, the fetus matures its organs so that they can adapt to outside life, it will stop feeding and breathing through the umbilical cord to do it directly through the oral and respiratory route. It is the period from which the fetus is viable abroad, so it is advisable not to make long trips or intense physical activity .
In any case, if we make the effort to be precise in the calculations, the nine months and 40 weeks from the last menstrual period, or 38 from the conception coincide in the same estimated date for the delivery .
How pregnancy is calculated
Popularly, pregnancy is calculated in months , and gynecologists calculate it in weeks, and it is very common that the accounts of one and the other do not coincide. The reason, on the one hand, is those two weeks of lag, which should not be taken into account, and on the other that we commonly equate the months to four weeks, which is imprecise, since most months have 30 or 31 days, which are not equivalent to four weeks.
In addition, this date is approximate, and most pregnant women give birth in the three or four days before or after that estimated date, which is when the 40th week is fulfilled , but there are also those that are advanced or delayed within the period that we consider normal for a full-term delivery, which is from week 37 to week 42 . Before week 37 it is considered preterm labor and after week 42 it is considered postmature .
Both one extreme and the other have risks for the newborn and should be avoided. Postmature pregnancies more frequently present fetal complications due to the aging of the placenta , and premature babies present the risk of the immaturity of the fetus that, although it has all its organs formed, is not prepared for life outside the mother’s womb prematurely. The more prematurity, the more problems it can present.
There have been cases of extreme premature infants, half a kilo and 24-25 weeks, who have survived, but frequently have health problems because neither their lungs are prepared to breathe, nor is their digestive system ready to absorb the nutrients from the milk … The more weeks in the womb, the better, until the end of 37-38 weeks.
In this regard, a popular belief is also confusing, which says that it is better for a premature baby to be “seven months old” than “eight months old”, nothing is more incorrect, the more weeks the baby has, the better!
What you should know…
- Pregnancy is the period between the fertilization of an egg and the birth of the newborn.
- Pregnancies are dated from the first day of the last menstrual period and the probable date of delivery is calculated 40 weeks later.
- Pregnancy is usually divided by trimesters , because each of them has its different connotations.