Demystifying pregnancy trimesters

by Media Xpose

What to expect, when you are expecting…

By Dr Kim Sonntag, MBChB (UCT) Dip Obs (SA) FCOG (SA) MMed (UCT)

Did you know?
-A pregnancy lasts approximately 40 weeks and consists of three trimesters.
-A term pregnancy starts from the first day of the last menstrual period to between 37-41 weeks.
-The first trimester is between 1-12 weeks, the second trimester is between 13-27 weeks, and the third trimester is between 28-40 weeks.

First trimester – time to start prenatal vitamins

The first trimester can be quite a difficult time, filled with many new and different pregnancy symptoms. Morning sickness refers to nausea and vomiting in pregnancy but can occur at any time of the day and may continue past the first 12 weeks.

Other symptoms include breast tenderness, fatigue, aversions to smells and certain foods, headaches and constipation. Many symptoms can be attributed to the change in hormones, with a rise in progesterone. The first pregnancy visit should be between 6-8 weeks and then every 6 weeks.

Blood tests will include a full blood count, blood group, HIV, syphilis and Hepatitis B screening. At 12-13 weeks a specialised foetal scan is done to screen for genetic abnormalities and pre-eclampsia (high blood pressure occurring in pregnancy).

The pregnancy starts as a small cluster of cells and rapidly grows into a small foetus. Organogenesis occurs during this time, which refers to the development of all the organs. From 6 weeks there will be cardiac activity, which can be heard as a foetal heartbeat.

It is important in this trimester to start prenatal vitamins, especially folic acid, which is vital to the development of the central nervous system. For the same reason it is important to refrain from drinking alcohol, smoking or using any medication that is not safe in pregnancy. This is the stage of pregnancy, the risk of miscarriage is significant.

Second trimester – foetal movements can be felt for the first time

The middle trimester is often the time where one feels the best in pregnancy. Energy levels return and nausea often subsides. The uterus starts to grow more rapidly, and a bump will start to appear.

Foetal movements can be felt between 18-22 weeks. Darkening of the skin occurs commonly on the face, areola of the breasts and a line running down the abdomen, called the linea nigra. Common complaints include heartburn, leg cramps and abdominal discomfort or pain in the sides of the abdomen called ‘round ligament pain’. Pregnancy visits would occur every 4 weeks, with a detailed foetal anatomy scan around 20-22 weeks to look closely at the foetal organs.

The foetal organs will grow and develop further during this period. There will be movement felt and the foetus will have periods when it is awake and sleeping. Skin, hair and nails have formed, and the foetus continues to increase in size and weight.

It is important to stay active at this stage of the pregnancy, which can improve discomfort and lower backpain. A screening test for gestational diabetes may be done, if you have risk factors for developing this pregnancy induced condition.

Third trimester – start preparing for birth

The third trimester begins at week 28 until the birth of the baby. Pregnancy consultations will be more frequent to ensure you are healthy and that the foetus is growing well. The uterus grows at a faster rate, which can lead to increased abdominal discomfort, heartburn, indigestion and shortness of breath. Constipation usually worsens, which can lead to the development of haemorrhoids and Braxton-Hicks contractions occur in the last few weeks of pregnancy. Breasts may begin to produce colostrum, which is a nutrient-rich form of breast milk.

The foetal organs and systems have formed and are maturing at this stage. The baby’s movement can feel more forceful and even cause discomfort. The foetus will drop lower in the abdomen and usually is in a cephalic (head down) position.

This is the time to start preparing for birth and deciding how to deliver the baby. Antenatal classes are commonly attended in the third trimester and decisions made regarding birthing preferences. A screening for Group B Streptococcus is done in the last few weeks of pregnancy. This is a bacteria which can be transferred to the foetus during delivery and can cause neonatal infection.

Fourth trimester – be aware of post-natal depression

The fourth trimester refers to the period just after the birth of the baby to 3 months postpartum. The body is returning to a non-pregnancy state, which takes at least 6 weeks.

Breastfeeding is established and a nurse or lactation consultant can assist with this. The uterus slowly starts to revert to its normal size and vaginal bleeding is to be expected for a few weeks.

A postnatal visit should occur at 1 and 6 weeks post-delivery to check the perineal area or abdominal incision if a caesarean section was performed. Contraception planning should also be discussed during this period.

This is also a time when one needs to be aware of signs of postnatal depression, which can include feelings of not bonding with the baby and hopelessness.

Dr Kim Sonntag is a specialist obstetrician and gynaecologist working at Life Kingsbury Hospital. She has a specialised interest in high-risk obstetrics and foetal medicine.

T          +27 (0)21 685 2375



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