Pregnancy consists of three stages, called trimesters:
First trimester (0 - 13 weeks)
The first trimester is a critical stage in the embryo's development. This is when the skeleton and organs take shape and is the time when congenital disabilities are most likely to develop. Miscarriages tend to be more likely to happen during the first trimester.
You won't have a bump yet, but the baby is likely to be making its presence felt in other ways. Morning sickness is typically worst during this stage. Other common symptoms are sore breasts, fatigue, and emotional ups and downs.
Second trimester (14 - 26 weeks)
Some of the early pregnancy symptoms like nausea and fatigue might ease during the second trimester. The fetus is growing bigger, so your bump is starting to show. You might begin to experience new symptoms, though, such as heartburn, backache, and leg cramps. Between 16 – 20 weeks is when you'll probably first feel the baby moving.
Third trimester (27 – 40 weeks)
You should have a sizeable bump now and be able to feel and see the baby moving. As the baby gets larger, it starts pressing on your organs and lungs, causing shortness of breath and problems like hemorrhoids, varicose veins, and urinary incontinence. You might also be having problems getting comfortable or sleeping properly.
At around 40 weeks, you start feeling contractions - abdominal pains that come in cycles – which signal the start of labor.