Attention, prospective parents, don't ignore these knowledge about birth defects

Author: Zhao Quming, deputy chief physician, Children's Hospital Affiliated to Fudan University

Reviewer: Huang Guoying, Chief Physician and Professor, Children's Hospital Affiliated to Fudan University

Birth defects refer to abnormalities in the body structure, function or metabolism that occur before the baby is born. They are the main causes of early miscarriage, stillbirth, infant death and congenital disabilities. According to the "China Birth Defect Prevention and Control Report (2012)", the total incidence of birth defects in my country is about 5.6%, with about 900,000 new cases of birth defects each year, and an average of one baby with birth defects is born every 30 seconds. Common types of birth defects include congenital heart disease, polydactyly, cleft lip and palate, hydrocephalus, hypospadias, etc. I believe that prospective parents must have many questions at this time: the proportion of birth defects seems not low, but our whole family is healthy, so the child should not get sick, right? What should be paid attention to during pregnancy to prevent birth defects? Can we ensure that the child will not get sick? If you have a birth defect, can it be discovered during pregnancy? Can it be cured? Let's talk about a few issues that prospective parents are concerned about.

What are the causes of birth defects?

There are more than 8,000 known birth defects, of which about 70% have unclear causes, and are mostly caused by complex combined factors. Some are indeed related to genetics, that is, if a family member has a birth defect, the baby's risk of the disease increases. Some are caused by chromosomal abnormalities or gene mutations in the baby itself. Other risk factors include older mothers (primiparas over 35 years old), taking special medications during pregnancy, alcoholism, smoking, infection or exposure to special chemicals. It should be noted that the presence of the above risk factors does not mean that the baby will definitely be affected, but it may increase the probability of birth defects.

Can birth defects be detected during pregnancy?

Birth defects may occur at any time during pregnancy, and most of them occur in the first 3 months of pregnancy. However, there are many types of birth defects, and the screening methods themselves have certain limitations. Even with regular prenatal examinations, not all birth defects can be detected during pregnancy. The "Guidelines for Ultrasound Prenatal Screening" issued by my country in 2022 pointed out that according to the current level of ultrasound technology, the main serious fetal structural malformations screened at 20 to 24+6 weeks of pregnancy include 9 types, namely: anencephaly, alobar holoprosencephaly, severe meningoencephalocele, severe open spina bifida with myelomeningocele, single ventricle, single great artery, bilateral kidney absence, severe chest and abdominal wall defects and visceral eversion, and lethal skeletal dysplasia with severe short limbs. The prenatal ultrasound detection rate of some fetal malformations is shown in the figure below.

Figure 1 Copyright image, no permission to reprint

Some birth defects, such as clubfoot, cleft lip and palate, or microcephaly, can be seen when the baby is born or easily found through physical examination. But more need to be found through newborn screening, including heel blood screening for genetic metabolic diseases, hearing screening, and congenital heart disease screening.

Figure 2 Copyright image, no permission to reprint

Can birth defects be prevented?

The health status, lifestyle, diet and medication of the prospective parents may affect the baby. Although there is no way to completely avoid birth defects, the following 5 points can effectively reduce the risk of birth defects in the baby.

1. Make sure to take 0.4mg of folic acid every day

Folic acid is a B vitamin that helps prevent neural tube defects (such as anencephaly and spina bifida) and also has a certain preventive effect on congenital heart disease. It is recommended that women who are planning to become pregnant start taking folic acid at least one month before pregnancy and continue taking it during pregnancy. In addition to taking vitamins containing folic acid, you can also consume more foods rich in folic acid, such as animal liver, eggs, beans, green leafy vegetables, fruits and nuts.

2. Take medication properly during pregnancy

If you are preparing for pregnancy, you may be taking related medications for various reasons. At this time, you need to consult a specialist or pharmacist about the safety of the current medications for the fetus. Although most medications are safe to take during pregnancy, some medications, such as some anti-epileptic drugs, cholesterol-like drugs, anti-allergic drugs, sleeping pills and anti-cancer drugs, have the risk of causing birth defects. At the same time, it is not recommended for women who are preparing for pregnancy to stop taking medications on their own before consulting a doctor, because the physical health of pregnant women is also very important.

3. Ensure necessary vaccinations

Getting the right vaccines at the right time during pregnancy can help ensure the health of pregnant women and fetuses. Inactivated vaccines are relatively safe for pregnant women. The "Technical Guidelines for Influenza Vaccination in China (2018-2019)" issued by the Chinese Center for Disease Control and Prevention recommends that pregnant women or women who are preparing to become pregnant during the flu season receive the flu vaccine, and pregnant women can receive it at any stage of pregnancy. In addition, imported hepatitis B vaccines, inactivated polio vaccines used for reinforcement or emergency vaccination during epidemics, rabies vaccines that need to be vaccinated due to exposure risks, tetanus vaccines and other inactivated vaccines can also be vaccinated during pregnancy. At the same time, there is a great possibility that the antibodies produced by the vaccine will pass through the placenta to immunize the baby. In general, expectant mothers need to get the right vaccines at the right time under the guidance of a doctor.

4. Try to achieve a healthy weight and blood sugar before trying to conceive

Obesity increases the risk of several serious birth defects and other pregnancy complications. Women who are obese before pregnancy (BMI ≥ 30) are also at higher risk of complications during pregnancy. In addition, if the mother has diabetes, it may also increase the risk of birth defects. When planning to have a baby, you need to consult a specialist for advice on controlling your weight and blood sugar.

5. Avoid exposure to harmful substances such as tobacco and alcohol during pregnancy, and prevent infection

Although there is no known safe amount of alcohol during pregnancy, exposure to alcohol may increase the risk of birth defects and other pregnancy complications. At the same time, smoking and even exposure to secondhand smoke may also cause harmful substances to damage the placenta and/or enter the fetus. In addition, some diseases that expectant mothers are infected with during pregnancy, such as rubella virus, cytomegalovirus, herpes simplex virus and some sexually transmitted diseases, may also cause harm to the fetus and even increase the risk of birth defects. At this time, you should see a doctor in time and receive regular examinations and treatment.

Are birth defects serious? Can they be cured?

Birth defects vary in severity, depending on the affected area and the extent of the damage. Some birth defects are mild and can be treated after birth, or even do not require treatment, with little long-term impact; some will affect the baby's life, causing mental or physical disabilities, requiring long-term treatment and support; and some will be life-threatening. In short, early treatment of birth defects is very important to prevent more serious complications, and treatment should be carried out in a timely manner under the guidance of a doctor.

If my baby has birth defects, can I still get pregnant again?

Even if you have had a baby with a birth defect, it does not mean that the baby you conceive later will definitely be affected by the same birth defect. However, if the birth defect is highly considered to be caused by family inheritance or gene mutation, you need to consult a specialist for genetic counseling to assess the risk of birth defects. The risk of some diseases can be determined by genetic testing before pregnancy, and genetic testing can also be performed on the fetus during pregnancy to determine whether the fetus carries a gene mutation that affects the previous child.