There are a number of changes a woman’s body goes through during the duration of pregnancy. The total duration of pregnancy is counted as 40 weeks of gestation which is from the date of the last period to the delivery of the baby. The conception or making of a baby occurs 2 weeks after the last period and hence an unborn baby spends around 38 weeks in the womb.
The duration of pregnancy is divided into three trimesters:
First trimester– conception to 12 weeks
Second trimester– 13 weeks to 27 weeks
Third trimester– 28 weeks to 40 weeks
First trimester of pregnancy
The first trimester of pregnancy ranges from conception to 12 weeks of gestation.
Signs and Symptoms of early pregnancy are:
- Missed periods
- Morning sickness, nausea and vomiting
- Breast tenderness
- General tiredness
- Increased frequency of urination
If you experience any of the above mentioned symptoms along with missed periods, you should take a pregnancy test to confirm pregnancy.
Important events during the first trimester are
Week 1: It is actually the date of menstrual period as it is included in the calculation of gestational age.
Week 2: Fertilisation of egg by sperm or conception takes place in this week.
Week 7: The heart of the embryo starts beating and this can be detected on ultrasound.
Week 10: The embryo is now known as foetus. Most of the body organs are formed. Fingers and toes start developing.
Week 12: The first trimester combined screening tests can be performed. These can be used to detect genetic and chromosomal abnormalities such as Down’s and Edwards syndrome amongst others.
Second trimester of pregnancy
The second trimester of pregnancy ranges from 13 weeks to 27 weeks of gestation. In the second trimester, morning sickness decreases but tiredness increases. Pregnancy may be visible and a steady weight gain is the norm.
Important events of the second trimester are
Week 13: The vocal cords of the foetus are now developed. The foetus can start sucking its thumb.
Week 16:The second trimester screening tests can be performed now in this week.
Week 18-20: An Ultrasound to check the size and position of the placenta should be performed. It can also check the morphology of the foetus .
Week 24: The skin of the foetus is now covered by fine hair or lanugo and protected by waxy secretions or vernix. It can also make breathing movements with its lungs.
Third trimester of pregnancy
The third trimester of pregnancy ranges from 28 weeks of gestation to the delivery. You may start feeling more tired. As labour approaches, it is normal to feel back pain, breathlessness or sleep difficulties.
Important events of the third trimester are
Week 28: The weight of the baby would be around 1000g and the length around 37 cm from head to toe.
Week 32: The movements of the baby are now strong and co-ordinated. The baby settles in the position for delivery. The most common position is head down but other positions are also present.
Week 36: Most of the babies descend into the pelvis by this time and are ready for delivery.
Week 40: It is the maximum time until which doctors usually wait for spontaneous labour. If pregnancy continue beyond this point, artificial labour can be induced.
