Third Trimester Question

heathert1981

Can someone tell me when the third trimester begins? I'm getting mixed reviews when I google it...

mrsjenni

26w6d... basically 27w.

krumca

You will probably get mixed reviews here too. It all depends on at what point you want to start counting from. If you count the 2 weeks before conception it's 26 weeks 6 days. If you don't count those weeks it's 25 weeks 5 days.

joshandpanda

mrs.jenni:

26w6d... basically 27w.

ditto... I see most people head over right at 27 weeks... 

mswood1977

There are 3 ways to calculate the trimesters, so depending on which method you use, you will have different date.

by Development:

This uses actual developmental stages to divide up a pregnancy. From LMP to 12 weeks the embryo develops all the major organs and becomes a fetus. From 12 weeks to 27 weeks the fetus continues developing and reaches viability. From 27 weeks on the fetus finishes development and prepares for delivery. Here the second trimester begins at 12w 0d and the third at 27w 0d.

by Gestation:

With this method you take the 40 weeks of gestation and divide into three equal stages. Here the second trimester begins at 13w 3d and the third at 26w 6d.

by Conception:

This method is where you take the 38 weeks of post conception development, divide by three, into the three equal trimesters. Here the second trimester begins at 14w 5d and the third at 27w 3d.

https://www.baby2see.com/trimester_calculator.html