Pregnancy, also known as gravidity or gestation, is the time during which a fertilized egg (zygote) develops inside a woman's uterus. Pregnancy is typically divided into three trimesters (trimenon) and lasts for around 267 days (40 weeks) [1] [2] [3]

The first trimenon (week 1-12)
The first trimester is from week one through 12 and includes conception. Conception is when the sperm fertilizes the egg. The fertilized egg then travels down the fallopian tube [FALLOPIAN TUBE] and attaches to the inside of the uterus [UTERUS], where it implants in the endometrial lining of the uterus.

After five weeks, pregnancy detection can be accomplished by urine or blood tests. The presence of human chorionic gonadotropin (hCG) which detect hormones generated by the newly formed placenta. [2] [3] [4]

In week seven, the heartbeat sets in and the fetus starts to react to external stimuli. By the end of the first trimenon, all compartments of the human body are established. [2] [3]

The second trimenon (week 13-28)
The second trimester is from week 13 through 28. The fetus' organs continue to grow, the face shows first facial expressions and hair starts to grow. [1] At week 24, the fetus opens its eyes and a wake-sleep cycle ensues. [5]
After five months the mother can feel the fetus move. [2] [3]

For many women, the second trimenon is the most relaxed phase of pregnancy because the body has become used to the elevated hormone level. By the end of the second trimenon a fetus is about 30cm in length and 1kg in weight. [2] [3] [5]

The third trimenon (week 29-40)
The third trimester is from 29 weeks through 40 weeks. During this time, the fetus gains fat in order to keep the body temperature after birth. [1] Shortly before birth, the space in the uterus is so scarce that the fetus can hardly move. [2] [3] In case of normal development, delivery takes place after 10 months. A regular neonate weighs between 2800 and 3500 g and is around 48-52 cm tall. [6]