Physiology of pregnancy

Pregnancy is always a pleasant surprise for many couples in the world and for the mother to be, it is a time filled with so many discoveries, aches, and excitement as she literally has a front row seat to one of the biggest and most complex miracles of nature, the development of a child from an embryo to a baby. The fathers to be are not left out as they also get to watch their creation develop from an embryo not bigger than a seed to a fully developed baby. For many couples, there is no greater pleasure than that and even when the mothers to be complain about the numerous changes that occur in their bodies and emotions as they grow their child, they do so with nostalgia and love because as tough as pregnancy can be, it is one of the most beautiful things to experience.

Pregnancy is the period when a baby grows and develops inside the uterus of a woman. It is a 40 week or 9 month period during which the fertilized egg grows and develops from an embryo to a baby. It is a period that comes with a lot of changes in almost every aspect of the woman's life especially physiologically and emotionally. Pregnancy occurs when a sperm from the male is able to fertilize an egg from the woman and fuse to form a zygote.

Signs of pregnancy

Pregnancy does not come with a single manual. Things would have been a while lot easier if it did. However, pregnancy is different for each woman. There are of course, the general symptoms that would indicate that there is a bun in the oven but many women have different symptoms peculiar to them. Here are the commonly experienced symptoms of pregnancy.

Nausea and Morning sickness

Almost every woman is clued in to the fact that she might be pregnant when she suddenly begins to puke every morning and generally feels very sick and lethargic in the mornings but bounces back with energy in the afternoon.

Absence of a period

Biologically, this should be the first clue that a woman is pregnant because once the egg has been fertilized, the body halts ovulation. However, some women have experienced spotting which seems a bit like a regular period but isn't.


When before getting pregnant you could work a 15 hour day without batting an eyelash and still not need to sleep for double that time, once you get pregnant, you begin to nod off by noon after withstanding the siren call of sleep for the past 2 hours. You find yourself adjusting your timetable as you go to sleep early, wake up late and still want to go back to sleep not long after that.

Breakfast becomes your enemy

You literally can't stomach eggs and the lovely smell of bacon makes you want to throw up your stomach contents.

These are examples of the things that should clue you in to the fact that you are going to be a new parent.

How to know if you are pregnant

If the signs above don't clue you in or you still want a confirmation of your pregnancy then you could do one of the following ;

  1. Buy a home pregnancy test kit. Read the instructions on it and follow them judiciously. In as little as a few minutes you should know if you need to prepare a nursery or not.
  2. Go to a hospital and do a blood or urine test so that you can be very sure that you are pregnant.

Stages of pregnancy and the physiological changes that occur during each one.

There are three stages of pregnancy and they are called trimesters.

First trimester

The first trimester spans the first three months which is 12 weeks. For most women, the first four weeks of the 12 week period goes unnoticed because they don't yet know that they are pregnant. In fact the symptoms that signal pregnancy begin to make themselves known in the second month for most and for others in their third month. So by the time they find out, most of the first trimester is gone. A lot of women after they found out that were pregnant, claimed that the first trimester was the hardest part of their pregnancy. It is quite understandable because in the first trimester, the woman's body is trying to eject the foreign body that has come to stay hence all the nausea and sick feelings.

Physiological changes in the first trimester

In the first trimester, there are quite a few not so physically noticeable changes that occur. The changes might be minuscule and only felt by the woman but nonetheless, the changes still occur.

First 4 weeks

The first 3 weeks you go about your normal duties unaware that inside your fallopian tube, the beginnings of a baby has begun with the fertilization of your egg by the sperm. It is during the fourth week when the fertilized zygote has moved into the uterus to attach itself to the uterine walls via a placenta that you begin to get clued in to the fact that you are pregnant. You begin to experience deep tiredness, morning sickness, abnormal cravings for things that you might have even hated before and you notice that you are more emotional than before. You could also experience mood swings. Your breasts swell up and feel sore, with visible veins, the aureola darkens and increases, and you begin to get more acquainted with the toilet. These are just signs that your body system is getting used to the stranger in its midst.

Week 5-8

Towards the second week of your first trimester, your baby has advanced so much that it now has a heartbeat though you can't hear it. It has developed a skull and the beginnings of a backbone. By the 6th week, you begin to feel a little bloated, wider in the waist area, and your clothes seem a little to small for you. Meanwhile your baby has started to develop limbs. As the 8th week approaches, your child has developed enough to have eyelashes and even though you know you are pregnant, you don't really see a stomach pouch. Your tummy still remains flat even though you have gained quite a bit of weight.

Weeks 9-12

In the last month of your first trimester, your stomach begins to show but not in a way noticeable to outsiders. With the end of your first trimester comes the end of the miscarriage risk period. You begin to notice that you need different bras because of the size of your breast.

The second Trimester

Congratulations for getting out of the miscarriage risky stage. Now, the second semester is when you begin to notice a lot of changes to your body. It is a generally accepted fact that the second trimester is the best part of the entire pregnancy.

Weeks 13-16

In this first four weeks of your second trimester, you can do some tests to make sure that everything is all right with your little one. Your stomach has grown a pouch which is smooth. You have begun to add a bit of weight as you stop vomiting in the mornings and start eating more. You would need to buy some new clothes to accommodate your growing stomach. Stretchy pants would be very appropriate. Your baby begins to develop teeth and bones and towards the last week, you begin to feel little flutters.

Weeks 17-20

By the 17th week, you child must have developed his reproductive organs and you can definitely find out the sex of your child. You would have also added a lot more weight and your stomach becomes bigger in size while your baby has a fully developed face and can even respond to certain stimuli such as light and music. You would experience a lot of tiredness and swelling in your feet. Try to rest whenever you're tired, don't over do it and frequently keep your feet up. Other sensations include dizziness so try not to make any sudden movements.

Weeks 21-24

You would need to have a mid pregnancy ultrasound and check up. Your baby would begin to develop a sleeping pattern and you would feel it's movements more. You would begin to notice an exponential increase in your stomach size and with this can come stretch marks on your breasts and stomach. You might also experience some leaking of breast milk from your breast. That is normal so try to wear a bra pad to prevent soaking your cloth. You begin to experience achy feet and back. Try not to do too much. Take things easy on yourself.

Weeks 25-28

This is the last four weeks of your second trimester and by now, you are noticeably 6 months pregnant. By now, you probably cannot see your feet and finding the right position to sleep in at night when you aren't spending half the time urinating, is difficult. You might feel irritated with quite a lot of things but you also feel excited and would likely try to put up your nursery. You are beginning to enjoy watching your child react to either your voice or his father's voice. The baby also begins to kick so you might be seeing a little feet kicking out against your abdomen. The organs of the baby have been developed and the baby also begins to grow fatter during this stage. You might also experience a lot of heartburn and a lot of fatigue. Be sure to put your feet up and rest. If your feet and ankles are swollen, you need to take your health more seriously than before. The swelling should go down and if it doesn't then you need to see your doctor posthaste before it turns to pre-eclampsia.

The third trimester

This is the last stage of your pregnancy, and arguably the second worst trimester for most mothers. At this point you must be feeling very fat, uncomfortable and ready to give birth. Relax, it's still a few months away.

Week 29-32

Towards the end of the 32nd week your very active child should have turned to face downward for birth. The baby also begins to have firmer movements and can focus his eyes on movement. Meanwhile you would be feeling very uncomfortable and ready for the end of your pregnancy to come. You feel very bloated and cramps are a part of your night. You find it more uncomfortable with each passing day to have a good sleep. Your stomach is very large by now and pressing even more on your bladder causing you to spend more time in the toilet. Your stomach also presses on your diaphragm and that might make you feel breathless at times. Just take it easy, you are almost there.

Weeks 33-37

At this stage, there really isn't a lot of difference in you physically except for the backaches and swollen feet. You look pregnant. Very pregnant. But the changes occur inside your uterus and with your baby. His bones harden except for those of the skull for easy delivery and then his lungs fully develop and he is ready for life outside the uterus. You need to rest up a lot because of the delivery coming up.

Weeks 37-40

This is the 40th week and the last month of your pregnancy. All you are waiting for now is your due date so that you can get officially introduced to your bundle of joy. Your baby too would be preparing to leave his temporary home by turning his head towards your pelvis. Once this happens, it is said that the baby's head has engaged. In just a few days, you would be meeting your baby.


Pregnancy is a really exciting journey right from when you realize you are pregnant right up to the time your child is ready to be born. Even though you get uncomfortable and deal with a lot of discomfort, enjoy each and every second of it because each week with you baby is precious and would not come again. Eat healthy, avoid any medication not prescribed by your physician and try to stay healthy. Happy pregnancy.