How oxygen and nutrients get to a fetus

Introduction:

I know you might have wondered what is going on inside a woman’s womb between the mother and the fetus (the baby). Well, am here to give you a little bit of the image of your imagination. To do that, I will be discussing on how blood and nutrients get to a fetus (baby still in the womb) from the mother.

Why does a fetus need blood?

A fetus more than any human needs blood because blood provides the baby with all required nutrients and other substances. A fetus undergoes vigorous cell division which brings about growth and development of its body. So many nutrients are needed for the supply of energy and other substances needed by its cells performing these functions.

Do pregnant women suffer because of these needs?

I would not use the word suffer because I think the woman’s body system is designed such that it can carry the stress of pregnancy till the end. That is why a pregnant woman is required to feed well, a food rich in essential nutrients and balanced. Extra stress is not allowed.

In order for easy understanding, I explain these terms:

Placenta: is a fibrous substance attached to the womb (uterus), having a fetal part and a uterine part. The umbilical cord from the baby’s umbilicus (navel) is attached to the fetal part of the placenta. From the uterine wall through this placenta (uterine part), blood containing dissolved oxygen, nutrients and other substances gets to the fetus (baby). Also carbon dioxide from the baby and other metabolic waste product from the baby get to the mother via this placenta.

Functions of the placenta – the placenta has two major functions; exchange of metabolic and gaseous products between maternal and fetal bloodstreams and production of hormones.

These metabolic and gaseous products include;

Gases (oxygen, carbon dioxide and carbon monoxide), because shortage of oxygen is fatal to the baby. It is worthy to note that the mother is the only source of oxygen because the lungs of a fetus do not work till birth.

Nutrients such as amino acids, free fatty acids, carbohydrates, and vitamins.

Maternal Antibodies (fights disease in the baby’s body system)

Production of hormones;

Hormones are produced by the placenta at the end of the fourth month of pregnancy. E.g. of such hormone is progesterone which help to maintain pregnancy.

Umbilical cord: this is a rope-like structure containing blood vessels that starts from the baby’s umbilicus or navel and ends on the fetal part of the placenta. Oxygen from the mother gets to the baby through the umbilical cord and carbon dioxide from the baby to the mother. The umbilical cord still attached to the baby after birth falls off few days after birth.

How does blood gets to the fetus from the mother:

There are 80 to 100 arteries called spiral arteries that pierce the placenta from the maternal side supplying blood into the placental spaces called intervillous spaces. Because the spiral artery is narrow, pressure is built up which forces blood into the uterine part of the placenta. From there, oxygen gets to the baby across the small villi through the umbilical cord by diffusion (the movement of particles or molecules from area where they are many to area where they are less, so that equilibrium may be attained). As the pressure decreases down the placenta, blood flows back to the mother via a vein called endometrial veins. This blood likely contains carbon dioxide from the baby (fetus).

In a matured placenta, the spaces (intervillous spaces) contain about 150ml of blood replenished about 3 or 4 times per minute.

There are four barriers which will decrease to two barriers in time that prevented the maternal blood from mixing with the fetal (baby’s) blood. These barriers are called the placental membrane and its decrease is to greatly increase the rate of exchange between the mother and the baby in the placenta. This increase of the rate of exchange is to meet up with the increase in demand of the baby (fetus) for these substances as the baby (fetus) matures.

There are numerous small villi deep inside the intervillous spaces which tend to provide a large surface area for the exchange of these substances. This way oxygen and other substances get to the fetus (baby) from the mother and carbon dioxide and other metabolic waste products from the baby gets to the mother.

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