Pregnancy: Delayed fetal development

What is a small fetus? What is the indicator for that?

Central estimation of fetus size depends on its weight, abdominal circumference, head circumference and bone length. The fetus is classified as small if its size is smaller than the tenth percentile - according to the generation of pregnancy, or if there is a severe deviation in the pace of its growth.

What are the risks of a small fetus?

The first and immediate risk is the presence of a pathological condition in the fetus - which in extreme cases may lead to his death in the womb, causing pathologies and hypoglycemia after birth. In addition, the small fetus has far-reaching effects, from attention deficit disorders to disorders in brain activity to stroke. The risk increases if the fetus, in addition to the delay in development, has anatomical defect or a chromosomal disorder.

Complications of pregnancy. Illustration: Shutterstock

What could be the causes of delayed fetal growth in the womb?

Genetic reasons: Some fetuses are young because those are their genetic characteristics (for example, fetuses for short people) - and there are no medical implications for their size.

An error in the pregnancy generation: incorrectly calculating the pregnancy generation may lead to wrong conclusions about the size of a healthy fetus.

Problems with the placenta: There are some factors associated with the placenta, which may lead to a delay in the development of the fetus inside the womb (for example: unstable placenta in place well, the separation of the placenta and others).

Exposure to intrauterine infection: Some infections that develop during pregnancy are transmitted to the fetus inside the womb, for example: CMV, rubella or toxoplasmosis-Toxoplasmosis. These infections may result in stopping the fetus's growth or its small size.

Fetal malformations or chromosomal damage: The more chromosomal abnormalities or damages - such as Down syndrome - the greater the probability of a small fetus being present for the generation of pregnancy.

Maternal causes: Maternal health has a major impact on the health of the fetus - and the health problems of the mother, such as chronic hypertension, thrombotic hypertrophy, persistent untreated diabetes, connective tissue diseases (such as systemic lupus erythematosus), anemia, hypothyroidism ( Thyroid disorders (not treated), chronic kidney disease and others. All of these problems can sometimes cause fetal development disorders.

Maternal weight before the camel and during pregnancy: very light weight or very heavy weight before pregnancy and / or no weight gain during pregnancy.

An external pathological environment: especially life in very high regions.

Which women are at risk?

As mentioned, women who suffer from a chronic disease and / or whose weight is light before pregnancy (less than 19 BMI) - or very heavy before pregnancy. In addition, this group includes women who have previously given birth to a small fetus; In addition to women whose families have a similar phenomenon.

How is the delay in the development of the fetus diagnosed?

During pregnancy, the fetal growth rate is monitored all the time, mainly through ultrasound examinations. In examining the late fetal organs scan, the fetus’s suitability for the pregnancy generation is tested - and if at this stage there is a gap between the size of the fetus and the pregnancy generation, the accuracy of the pregnancy generation is more accurately verified again; And if it becomes clear that the gap still exists, the reason for the delay in growth is examined, as it includes all of the above. If it appears in the fetal organs scan that the size of the fetus is appropriate for the generation of pregnancy, a new examination is carried out in the week 32-24 of pregnancy - then one or two estimates of the weight of the fetus and the rate of its development are performed.

Can fetal development delay in the womb be prevented?

First, care must be taken to receive vaccinations to prevent delayed development of the fetus due to infections such as rubella.

Women who have had previous experience of delayed fetal development due to a problem with the placenta - should undergo checks for various disorders such as hypertension, hypercoagulability, etc.

Women who suffer from chronic diseases should treat these diseases in order not to cause complications; Also, women who weigh very little before pregnancy or are very heavy should go to a nutritional counseling before pregnancy in order to start pregnancy with the appropriate weight.

Can the problem be remedied?

To this day, no actual treatment for this problem has been available. This is due to the inability to determine what is happening inside the womb - in most cases, delayed growth is detected at a stage when we do not have the ability to provide intrauterine therapy.

What should we do when we discover a delay in the development of the fetus?

When a delay in the development of the fetus is discovered, the woman is transferred to treatment and follow-up in the high-risk pregnancy centers - there is a frequent monitoring of the development of the fetus, the amount of amniotic fluid and blood flow in the arteries of the uterus and fetus.In addition, tests are carried out that include screening for placenta disorder, infections, or chronic maternal diseases, and sometimes genetic counseling and amniocentesis are obtained in order to obtain chromosome characteristics in the fetus; If the fetus continues to grow according to its normal pace and all tests are intact, we allow the woman to reach her normal date of birth.

If there are other disorders, changes in the monitoring of the fetus’s heart, a complete stopping of the fetus’s development, disorders of blood flow in the fetus or in the mother, as evidenced by Doppler tests - the mother is hospitalized and a decision is made individually regarding its birth, as it is in the form of A year, before the 34th week of pregnancy, treatment is provided for the maturation of the lungs - and a decision is made whether to deliver the baby in order to avoid severe illnesses or the death of the fetus inside the womb.

In order to avoid a repetition of young fetuses in the next pregnancy, it is important to examine the placenta after childbirth and you should receive advice from specialists in the field of high-risk pregnancy. It is also possible that there will be a need for genetic counseling and testing for parents.


Professor Ofer Ayers is Alternative Director of the Department of Births D, the obstetrics and gynecology ward at Soroka Medical Center in Beersheba.