Pregnancy calendar – what happens in the mother’s belly during each trimester

The pregnancy calendar tells precisely what is happening in a woman’s body during the long nine months of pregnancy week by week. A detailed description of the development processes of organs, limbs and systems helps determine which week of pregnancy a woman is going through. Based on the pregnancy calendar, it is possible to determine, with some caution, the approximate date of delivery. However, it is worth noting that there are also terminations at 41 and even, in rarer cases, 42 weeks of pregnancy.

40 weeks of pregnancy

• 1 trimester

The 1st week of pregnancy is counted rather perversely, because from the first day of menstruation, and therefore from the moment when the woman is not yet pregnant. The beginning of the fertile period is in the 2nd week of pregnancy, when the uterus is just preparing for fertilization, which generally occurs between the 12th and 16th day of the cycle. Proper fertilization does not occur until the 3rd week of pregnancy. The blastocyst, or future baby, measures 1.7mm at 4 weeks gestation, and is therefore smaller than the head of a pin. In the 5th week of pregnancy, the processes of organogenesis, or organ development, begin. Very intensive growth occurs between the 6th and 7th week of pregnancy – the embryo can grow up to 1 mm per day. At 8 weeks of pregnancy, the ultrasound image already shows hands and feet, the intestines are also developing and the future skeleton is delicate and fragile. In the 9th week of pregnancy, intensive brain development occurs and the fetus begins to move. From the 10th week, the fetus begins to sense its mother’s emotions, so it is important to keep stress to a minimum. At the end of the first trimester, along with nausea passes the most risky period (due to miscarriages).

•  2nd trimester

At 14 weeks of pregnancy, the baby already weighs 50 grams and measures 10 centimeters. Over the next 14 days, the pregnancy already becomes visible to those around it. During the 19th and 20th weeks of pregnancy, the baby’s hair is already growing, the ovaries of teeth are appearing, and the baby itself is becoming very active, which is perfectly sensed by its mother. Generally at the beginning of the 21st week of pregnancy until the end of the second trimester, the toddler has all his senses developed, hiccups happen, he kicks hard and already weighs more than 1 kilogram. When a pregnant woman eats something sweet, her fetal waters become so attractive to the baby that it begins to swallow them greedily. Receptors to the sweet taste are then very sensitive.

• 3rd trimester

The 28th week of pregnancy is the beginning of the last trimester, which will end in labor. At 29 weeks of pregnancy, the baby can already see and hear perfectly. During the 30th and 31st weeks of pregnancy, the baby’s immune system is strengthened. During this period also the baby slowly begins to position its head towards the uterine outlet, a sign that labor is getting closer. During the 32nd week of pregnancy, the baby is still gaining weight, and the ultrasound shows him sucking his thumb. At 33 – 34 weeks of pregnancy, premature labor may occur. During this time, the fetus accumulates large amounts of iron and builds up fat reserves. However, at this stage the lungs are not yet fully developed, so the most common problem for premature babies is breathing on their own. From the 36th week of pregnancy, the baby is already practically an independent entity and can live outside its mother’s body. From the 37th week until the end of pregnancy, the baby already has everything it needs to live outside the womb. Its lungs, brain, heart and other internal organs are strong and fully developed. Now all that remains is the delivery.