Is it a twin line flashing on your pregnancy test strip? Congratulations Mommy-would-be! Definitely, you are wondering how old the little darling inside you is? Just after your heart settles from the horripilation, you delve down in the PREGNANCY MATH. Check out these simple tips to resolve to how to calculate Pregnancy in weeks and months.

Before you encounter questions just quickly recapitulate if you remember your Last Menstrual Cycle (LMP) which is a vital point.

When is my due date?

How many weeks Am I Pregnant?

In which trimester what sort of care I should take to keep myself and my baby in best health condition?

So here we are with all easy solution and answer to your questions.


It is best to consult a gynecologist at earliest who can determine all details based on CRL or Crown Rump Length determining the gestational age of the baby.

Average Duration


Formula for self-calculation;

1st day of LAST Menstrual Period (LMP) + 40 weeks

Example – If your 1st day of LMP was 20th Feb 2018 then

Solution – 20th Feb 2018 + 40 weeks = 27th November 2018 is your due date of delivery


General formula of calculation by Physicians;

9 months + 7 days of your 1st day of LMP

Solution – 20th Feb + 9 months = 20th November 2018

20th Nov 2018 + 7 days = 27th November 2018

However, out of 20 babies, only 1 takes birth on the due date.

[icon type=”icon-lamp”] Still not able to calculate your Pregnancy in weeks and months? Use Budding Star’s Pregnancy Due Date Calculator for knowing how many weeks pregnant you are just by entering the first day of your last period.

CRL or Crown Rump Length in getting gestational age of the baby:

Crown Rump Length refers to the measurement of the length of human embryo or fetus. Generally, the length is considered from head to bottom of buttocks. This is done by ultrasound scan. The size and length determine the exact gestational age of the baby. On every trimester ultrasound should done to know the position and other specifications of the baby.

Weeks Chart of Pregnancy Months:

Divide 9 months by 3 trimesters

First Trimester1-13 weeks + 6 days1 to 3
Second Trimester14-27 weeks + 6 days4 to 6
Third Trimester28-40 weeks + Date of delivery7 to 9

Week is just calculated like your age. The first year of baby birth is considered as 0 year and respective months. And by the time baby complete one full year and drop to the second year he/she is said 1 year old. Similarly, when you are on your 2nd week you are been said as 1 week pregnant by a physician. So formula is;

  X+1 week = X week

Example – 12 +1 week = 13 week

13 is medically considered as 12th week

 Trimesters & Developments & Problems:

  • First trimester – The mass of cell or embryo starts taking shape and the first organ that develops in the fetus is Heart. On the third week, you can hear the heartbeat of the tender life inside you. Take care of your nutrition as the same is nurturing the baby too. It is the toughest phase hence morning sickness, nausea, and weight loss may happen.
  • Second Trimester – In these months fetus gets well-defined face, eyes, eyelids, toes, hands, nails and other organs also develop. These days you feel much better. You may gain weight, get a baby glow, feel more relaxed as by now you are used to and know your next step.
  • Third Trimester – These months baby can hear, respond to light and touch, can kick and move heads. You are about to deliver and so need to be very cautious.
[icon type=”icon-lamp”] Come along! Let us explore the world of Pregnancy week by week by looking at fetal development, moods & symptoms with do’s and don’ts and pregnancy-related frequently asked questions.

Strictly maintain Dos & Don’t by Doctor. Take proper precautions, don’t miss out any medicine, and take medical help without any delay in case you doubt any complications.

Happy Pregnancy!

About alka

Recently reinvented her old love of writing. A Literature graduate from Delhi university had a flair for writing ,and has also written for her college magazines and has also done dialogue writing for college drama.
She later on pursued MBA in Human Resources and Marketing with over 4+ years of experience with international exposure. Has been married for more than 8 years and leads a Blissful life with her husband and a son of 6 yrs

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