Gestational Phases of Humans & Age Calculators

Gestational_Phases_calculationGestational phase is the time for which the foetus remains within the uterus of her mother and his birth. Normal gestation period varies from 37 weeks of pregnancy to 42 weeks. Generally, due date is calculated by knowing the last menstrual period of women. However, mostly delivery occurs around the due date and not exactly on the predicted date.

There are different stages of human gestation defined as follows: 

First Trimester:

This is the time period from the onset of pregnancy till the 13th week of pregnancy. This is an important time in a planned pregnancy which requires follow-ups and Ultrasound. In this phase:

  • Mother feels morning sickness. It is a feeling of nausea, vomiting and fatigue.
  • Foetus isn’t large enough yet so the mother will not feel any movements.
  • Mother should take care of medicines used.

Second Trimester:

This period starts from the 14th week of pregnancy till 27th week. During this period Ultrasound is again performed but the purpose is different from first trimester i.e. detecting any congenital disease. In this phase:

  • Mother feels better as morning sickness is gone.
  • Baby his growing rapidly. By the 20th week most women start feeling the foetus usually felt as ‘’butterfly waving its wings’’.

Third Trimester:

This period begins from the 28th week of gestation and ends at delivery/birth of child. During this period foetus growth further in size stretching the abdomen and uterus of mother. It this phase:

  • In beginning of first trimester foetal movements are active as it grows and occupies more space the movements will taper down in frequency but will be stronger and uncomfortable.
  • During last 2-3 weeks of gestation period contractions will ensue. These contractions are for the purpose of pushing baby through the birth canal as a preparation of birth.

Normal delivery will be performed after up to 24 hours of labour. If the location of baby is not appropriate physician will plan a C-section. If labour and delivery hasn’t occurred till 42nd week of gestation, physician may induce labour.

Factors Influencing Duration of Gestation Period:

  • A delayed increase in progesterone levels cause shorter gestational period.
  • Older women have longer gestation.
  • Women with increased weight have longer gestation.
  • Women who have a previous history of longer gestational period are more predisposed for having it once again.

Gestational Age Calculators

These calculators are available on internet easily these days. However more reliable methods are performed by doctors in clinic:

Methods in Clinic:

  1. The first method is clinical examination, which will be performed by your doctor with inquiry about your conditions and medical history.
  2. Second method is Doppler Ultrasound which is done at 12 weeks.
  3. Third test is Human Chorionic Gonadotropin Test which helps to estimate the gestational age. This test provides results on 6-14 days after women conceive.

Online Ways:

Online ways for knowing gestational age can be accessed by going on to the following links:

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