In this 21th week of pregnancy, the fetus measures 25 cm. the baby’s weight at 23 weeks is approximately 450 g. It is therefore 100 times larger than at the end of the first month. From now on, it will grow more slowly – it will only double its size to eventually reach some 50 cm – but multiply its weight by around 6.

His movements are more and more tonic.

Her nails and hair are growing.

With its senses maturing, the 23 year old baby is very attentive to different stimuli, sound or tactile.

He perfects his sucking reflex, essential at birth for nourishment, by absorbing amniotic fluid or sucking his thumb, which he is now able to put in the mouth.

The lungs of the 21 week fetus are still filled with fluid and within them, the respiratory alveoli continue to develop, but the baby increasingly performs so-called pseudo-respiratory movements of the chest.

This is half of the 2nd quarter and the placenta has finished its development. Until the end of pregnancy, the villous membrane will thin in order to promote the foeto-maternal gas and nutrient exchanges. It’s the 5th month of pregnancy, the placenta also secretes hormones essential for the successful continuation of pregnancy: progesterone and estrogen. This is often referred to as a “placental barrier” because the placenta, like a filter, prevents certain substances from passing through and reaching the fetus. However, this barrier is not completely waterproof, and certain molecules potentially dangerous for the baby can cross it: drug molecules, the different components of cigarettes, those of alcohol, certain food bacteria, etc. Caution therefore remains in order.

Four months pregnant, the uterus weighs around 700 g – compared to 200 g in the 8th week and between 800 and 1200 g at term (1).

The breasts, which have been preparing themselves from the start of pregnancy for their future nursing function, begin to produce colostrum, this thick, yellow liquid that is extremely nutritious which will nourish the baby for 2-3 days before the flow of milk. During pregnancy, this colostrum is normally reabsorbed by the body, but it happens that a few drops flow through the nipples, without this being abnormal.

With a belly that is growing more and more in this 3rd week of amenorrhea, i.e. 21 SG, altering the balance of the body and starting to compress the surrounding organs, lower back pain, ligament pain, urgent urge to urinate are common ailments at the end of 5th month. Small digestive concerns can also persist: constipation, gastroesophageal reflux.

Some fatigue can also be felt, especially as slight sleep disturbances can also appear. Indeed, it becomes difficult to find a comfortable position, and the prospect of childbirth and her future role as a mother can give rise to various anxieties in pregnant women.

When for his 5th month of pregnancy, the risks of iron deficiency are rather high. The body is not able to synthesize this mineral. It must therefore be found in the diet. The mother-to-be must provide the fetus in sufficient quantity, because its needs increase. Iron helps transport oxygen from mother to baby and is actively involved in making red blood cells. The blood volume increases and therefore so does the need for iron. The pregnant woman can also be anemic and very tired. The iron therefore allows her to keep a certain strength and sufficient energy for the smooth running of the pregnancy. To the 21th week of pregnancy, tablets prescribed by the doctor can be taken by pregnant women. Otherwise, a diet rich in iron can ensure these roles and prevent possible inconvenience in the mother-to-be. Legumes (chickpeas, lentils, beans) contain a good quantity of it. It is very important to avoid too much iron deficiency in pregnant women, as this can deplete them and cause premature labor. 

• make an appointment for the next consultation;
• take stock of their birth plan;
• start thinking about the baby’s name if it is not already found;
• continue shopping for the baby and in particular his keychain, now that his gender is generally known (for parents who so wish);
• perform monthly examinations: urinalysis for sugar and albumin, toxoplasmosis serology for non-immune pregnant women, search for irregular agglutinins if the mother is rh negative;

During pregnancy and childbirth, the perineum, this set of muscles and ligaments which, like a hammock, supports the organs of the small pelvis, is highly stressed. To tone it, soften it and thus preserve it, it is advisable to practice small daily contraction and relaxation exercises. To the “pee-stop” (exercise consisting in stopping urinating at the beginning of urination), we prefer the “false pee-stop”: tighten the perineum for 5 seconds while pretending to stop urinating, then relax the perineum for 10 to 15 seconds. Repeat ten times (2).

In addition to the small exercises to be performed on a daily basis, the perineum massage can be performed. The expectant mother usually starts doing it from the 8th month of pregnancy, but she can massage her perineum from this time on. 21st week of pregnancy, i.e. 23 weeks. The sooner it does it, the better. It is the pregnant woman herself who practices it using an oil specially designed for this particular area. The perineum massage has several functions: it allows the woman to better understand her anatomy and also to relax the muscles of her perineum. This prevents possible tears during childbirth.  

Beware of passive smoking: the substances contained in cigarette smoke are inhaled by the expectant mother, pass into her blood and therefore into that of the fetus via the placenta, which does not filter all the chemicals. A study (3) has thus demonstrated levels of nicotine in the amniotic fluid in pregnant women who do not smoke but exposed to tobacco, as well as in the urine of the baby at birth.