The Three Phases of Pregnancy
Nine months can seem like a long time when you’re pregnant.
You’ve probably heard the term “trimester” before, which refers to each of the three phases of pregnancy. Which each phase of pregnancy comes different developmental stages for the fetus and different experiences for the mother.
These trimesters start from the first day of your last menstrual period and each last an average of three months. Every week there are different developmental changes happening inside a woman’s body. It’s a lot of information, but it’s important to know what’s going on during the three phases of pregnancy.
Week 1 – Week 12
After conception, the fertilized egg begins to develop into a clump of cells. In order for this organism to survive and grow, it must implant itself on the uterine wall. Once attached to the walls of the uterus, the embryo can then receive the proper nutrients and hormones from the mother’s body so that its cells can continue to duplicate and grow.
This implantation phase of the first trimester will trigger hormonal shifts and changes in a woman’s body. Women will often experience the most severe morning sickness during these early months because of the vast hormonal and biological changes happening within her body.
Starting around Week 3 of the pregnancy is the embryonic state, which begins after the embryo successfully implants itself on the walls of the uterus.
In this phase of pregnancy, three key developments will happen:
- The embryo will create all its major bodily organs, including the heart, face, muscles, sexual organs, and nervous system
- The placenta is created to deliver nutrients to the growing embryo through the umbilical cord
- The amniotic sac and fluid will develop as a protective layer inside the uterus
After all of these major developments, the fetal state will begin in the last tween weeks of this first trimester. In this time, the fetus will triple in length by Week 12, have functioning kidneys, and will grow fingernails and toenails.
Making the Announcement
It is often the case that couples or expectant mothers choose to wait until after the first trimester to make news of the pregnancy public since there is a higher risk of miscarriage in the first few months.
Week 13 – Week 27
The fetus’s organs will have fully developed during the second trimester and it will also gain the ability to both hear and swallow. It is also during this stage that you can begin to feel the fetus moving and kicking, a sensation that can first be felt typically between Week 18 and Week 22.
In the second trimester, the fetus is growing to put on more weight by accumulating more cells and building up more fat. It can now grow hairs and develop sleep patterns. By the end of this phase, the fetus will weigh an average of 1.5lbs and will be about 10in long.
Most women won’t start showing a visible baby bump until part way through the second trimester which starts around the third month of pregnancy. The bodily changes that happen in the second trimester can lead to stretch marks on the skin of the abdomen, around the breasts, or in other areas of the body to accommodate all of these change. At this stage, women may also experience an increase in appetite, swelling in her joins (especially the hands and ankles), and bodily aches.
Week 28 – Birth
In the third trimester is like the light at the end of the tunnel is finally visible.
Here’s a bit of what’s happening developmentally: eyelashes have formed and the fetus will be able to open its eyes; the nervous system is strong enough to control the body’s temperature and also rhythmic breathing; around Week 29, the fetus has a greater range of motion and can stretch and kick. Hair can also start to grow on the head.
Once all of the major development is mostly complete, it’s time for rapid weight gain in the last few weeks. By Week 32, the fetus practices breathing and works to further strengthen and develop its lungs. Towards the end of the third trimester a fetus’s pupils and respond to light by changing sizes. All of the bones, besides, the skull and a few others, are hardening by this point.
The longer the fetus can remain in gestation in the womb, the stronger it’s organ can develop, especially the lungs. Of course, every woman has a due date, but a variety of factors will contribute to the timing actual birth. The normal gestational period is forty weeks, though a preterm delivery can sometimes safely occur as early as 23 weeks.
Click here to learn more about the stages of fetal development in the three phases of pregnancy.
Contact White Rose Women’s Center for more questions about pregnancy.
Here at White Rose, our experienced staff is committed to explaining all of your available pregnancy options and help you make the choice that’s best for you.
White Rose is proud to offer women FREE pregnancy tests (and give you the results as you wait) as well as FREE and confidential counseling.
Some other services which White Rose Women’s Center provides:
- FREE ultrasound for qualified clients
- Information on abortion procedures
- Referrals for prenatal care
- Clinic referrals
- Post-abortion guidance
- Adoption referrals
- And more!