The first trimester refers to the first 12 weeks of pregnancy. It’s an exciting time, but it’s also critical because it is when the baby develops all the major organs. During the first trimester, the baby’s brain and nervous system develop. The heart starts beating, and blood flows through the veins and arteries. The arms, legs, and backbone form, and the baby’s organs also start to develop, including the lungs, liver, and kidneys. Here is what to expect during that time.
Fertilization of the egg – The first trimester is when the fertilization of the ovum occurs. The sperm has to reach and penetrate an egg for this to happen. If it doesn’t, pregnancy will not occur.
Implantation – Once conception happens, the zygote attaches itself to the mother’s uterus lining through implantation, which usually occurs about a week after fertilization.
Hormonal changes – The body’s hormone levels go up in this trimester during the first few weeks. This will cause the pregnant to feel nauseous and tired during this time because her body is working hard to support the baby.
The heartbeat – At six weeks, the baby starts developing their neural system along with its heart beating for the first time.
Baby’s head develops – At seven weeks, the baby has developed his or her head. The brain and the face continue to grow at this stage.
Other features start to form – At 8 weeks, the baby’s limbs and fingers start to form, and swellings outlining the ears and eyes also form. At this stage, the nose also forms, and the toes appear at week 9.
The elbows can now bend – In the 10th week, the baby’s eyelids, mouth, and chin are recognizable. The baby’s head is now more round, and they can bend their elbows. The baby is also starting to move around in small movements, although the mother can’t feel it yet.
Baby’s genitalia form – The baby’s external genitalia start to form towards the end of week 11. Red blood cells also start forming in the liver at this stage. During this week, the baby officially becomes a fetus.
More features develop – During this week, the fetus’s fingernails form. Their head becomes more developed, and the intestines form in the stomach. At the end of this week, the baby is about the size of a peach.