How Long Is Pregnancy ?

by Pranjul Kapur Tandon
5 minutes read

Most humans associate the length of pregnancy with the magic digit of 9. Pregnancy is universally regarded as being 9 months long and is divided into first, second and third trimester. But is the pregnancy math that simple? Are babies born exactly when the 9 calendar months are crossed?How Long Is Pregnancy ?

The Pregnancy math 1

Image Credit :thestagesofpregnancy

Pregnancy is always calculated from the first day of your last menstrual period even though the baby has not been conceived at that time. The reason behind this is that you can never be sure about the actual date of conception (it can happen anytime within 5 days of having intercourse during a woman’s fertile cycle) whereas most women accurately remember the first date of their menstrual cycle.Hence, medically, the first date of last menstruation cycle is considered the start date of your pregnancy.

The Pregnancy math

Image Credit : howstuffworks

Doctors regard 280 days or 40 weeks since the start of last menstrual cycle as the average human gestation period. As a general rule, doctors calculate your due date to be 40 weeks post the first day of your last menstrual cycle. Any baby born between 38 weeks to 42 weeks is considered a full term baby and is ready to survive outside of womb.For example, if a pregnant lady got her cycle on 1st January, your medical due date would be 7thOctober. However, you will be ready to welcome your baby anytime between 16th September to 21st October. Thus, we see Due date just gives us an approximate idea of the baby’s arrival and most women don’t necessarily give birth exactly on their due date.

If a woman doesn’t have regular menstrual cycle or does not remember the dates of her cycle correctly, it will be hard to point her due date according to the 40 weeks rule. The doctors in that case estimate the possible birth date according to baby’s growth in the womb. The medical advancement these days makes it possible for the doctors to get a very good idea of the fetus’s exact weight and size using the latest scanning and imaging techniques.

The Pregnancy math 3

Image Credit :motherandbaby

Pregnancy is also divided into trimesters. The first trimester is from the first day of menstruation till the end of week 12 (approximately the first three months). Second trimester is from the start of week 13 till end of week 27 (approximately the middle three months). The third trimester is from start of week 28 till birth (approximately the last three months).

The Pregnancy math 2

Image Credit :child-development-guide

Your body and the baby inside do not follow the man-made calendar and have their own impeccable timing. A healthy body beautifully nurtures the fetus till it is fully developed to survive in the outer world. This is the reason why a baby born at the start of 38th week can be as healthy and well developed as an infant born after 41 weeks and 6 days. This is also the reason why birth is regarded as a miracle of nature!

The author is a CAPPA  certified childbirth educator.

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Leave a Comment


Apoorwa April 11, 2018 - 5:01 PM

I was knowing all these things … But you had written it in a vry interesting way pranjul… :balleballe I enjoyed reading it pranjul ! :rose:

Deepsikha April 12, 2018 - 8:06 AM

Such an informative post!
Thanks for this! :haanji

Smriti April 12, 2018 - 9:59 AM

ah, i didn’t know many a things. very informative article…

Sreeparna Ganguly April 13, 2018 - 1:20 PM

Interesting.. :love
I used to wonder how do the baby birth date is predicted.. Now I know :haanji