So, this means when your doctor tells you you're four weeks pregnant, your baby's gestational age is actually two weeks.Trimester means 'three months', so your pregnancy will be divided into three trimesters.There are a number of methods that are effective, including pills, implants, injections, IUDs, and condoms.
If either of you has any doubts, use condoms every time.
Your third trimester is from 28 weeks to when you give birth.
Although all babies grow at different rates, you can work out how big your baby is in terms of the fruit and veg you might recognise in the supermarket here.
During the scan, the sonographer will look at how developed your baby is and measure the length of your baby from his head to his bottom, which helps them to give you an EDD (estimated due date) based on how far along in your pregnancy you are.
They will also check you are only expecting one baby not two, and that your baby is developing in the right place. It can be tricky at first to work out how to count your pregnancy in weeks and months, as when we measure your pregnancy from the start of your last period, your baby is actually two weeks younger than the pregnancy start date, otherwise referred to as the 'gestational age'.