Teratology and Drug Use During Pregnancy

Introduction:

Teratogens are drugs or chemicals that can cause anatomical defects in a fetus. A teratogenic agent is responsible for causing deformities in the fetus. The majority of agents that come into contact with are not proven teratogens. However, some medications, chemicals, and infections can cause deformities or defects in the fetus. Discussing with a doctor before pregnancy is crucial to know more about teratogens. This article also provides knowledge about drugs and other agents that can cause birth defects in babies.

What Is a Teratogen?

Teratogens are drugs, radiation, chemicals, or even infections that can cause abnormal fetal development. A teratogenic agent is responsible for abnormal fetal development. There are many teratogens; however, only a few agents are found to have teratogenic effects. About four to five percent of congenital defects are caused by exposure to a teratogen.

The doctors believe a teratogen can affect a fetus about 10 to 14 days after conception. During embryonic development, the developing organ systems are more sensitive to teratogens. Especially if exposure to a teratogen agent occurs during the 3.5 to 4.5 weeks of pregnancy, neural tube defects can occur. Avoiding medications and other teratogenic agents is the ideal way to reduce the risk of teratogenic exposure during pregnancy.

What Are the Drugs That Affect the Fetus?

Pregnant women should be educated about the use of drugs to cope with aches, pains, tension, and viral illnesses during pregnancy. Medications should be used only when required and with a doctor's recommendation because some drugs have the ability to cause birth defects in newborns.

1) Aminopterin - It is a drug used to treat cancerous tumors. This drug blocks folic acid, which is important for cell growth and DNA production. Folic acid also helps prevent many birth defects, including neural tube defects. So when aminopterin is used during pregnancy, it can lead to brain abnormalities such as hydrocephalus (fluid buildup in the brain) and anencephaly (all or part of the brain is missing). This medication can also cause facial abnormalities like cleft palate and cleft lip.

2) Anticoagulants (Warfarin and Heparin) - Warfarin can affect the central nervous system and cause intellectual disability and even problems with the optic nerves. Heparin can cause bone demineralization, which can decrease the bone density of the baby and cause spine fractures.

3) Antiepileptic Drugs - These drugs are associated with a wide range of birth defects, such as cleft palate, microcephaly (a condition causing the brain to be too small), and cardiovascular abnormalities. These drugs include Trimethadione, Valproic acid, and Phenytoin. However, women with epilepsy need a change in medication and special monitoring and care during pregnancy.

4) Angiotensin-Converting Enzyme (Ace) Inhibitors - This drug treats high blood pressure. ACE inhibitors can cause several problems during pregnancy, like problems with the baby's kidneys, fetal growth restriction, and sometimes even the baby's death during pregnancy.

5) Isotretinoin - This drug is used to treat severe acne. It can also cause a number of congenital abnormalities that include cleft palate, abnormalities of the outer ear, underdevelopment of the lower jaw, heart defects, and neural tube defects.

6) Corticosteroids - These drugs are given to mothers with asthma, and they are often not harmful. But in a few cases, cleft lip and palate have been reported in a few infants.

7) Selective Serotonin Reuptake inhibitors (SSRIs) - These drugs treat depression. They can cross the placenta and affect the fetus. Most of the effects in the fetus are subtle and include agitation, tremor, irritability, increased respiratory rate, diarrhea, and nasal congestion. However, Paroxetine is a kind of SSRI that is thought to cause congenital abnormalities in early pregnancy. It is also necessary to remember that depression itself may be more deleterious than the drugs used to treat depression. So it is important to discuss the benefits of SSRIs in treating depression, which needs to be weighed against the complications to the unborn baby.

8) Tranquilizers - These are drugs used to treat anxiety, such as Lithium, Phenothiazine, and Diazepam, which are thought to be teratogens. These drugs are linked with birth defects such as cleft lip or palate.

9) Antifungal Drugs - Fluconazole is an antifungal drug; when this drug is used during the first trimester of pregnancy, it has a high chance of causing limb deformities in the newborn.

10) Hormones - Hormones like progestins and androgens have been proven to make female babies more masculine. The clitoris of the female baby may be larger than normal. The outer lips covering her genitals may be fused.

11) Diethylstilbestrol (DES) - It is a form of estrogen that can cause abnormalities of the vagina, uterus, and cervix in female fetuses.

Can Substance Abuse During Pregnancy Cause Teratogenic Effects on Babies?

Yes, substance abuse is a common cause of fetus deformity. Some of the common substance abuses that have teratogenic effects on the fetus are as follows:

1) Alcohol - Alcohol use, even in small quantities, can cause congenital abnormalities during pregnancy. Deformities of the arms, legs, and face, heart conditions, fetal growth restriction, and intellectual disability are the abnormalities caused by alcohol in pregnancy, but these are not common. Problems with behavioral and thinking, and remembering issues are common problems seen in children of alcoholic mothers.

2) Smoking - Cigarette smoking during pregnancy can cause premature birth and fetal growth restriction. It can also cause problems with the cardiovascular system, development of the brain, and respiratory system. These can also happen when exposed to second-hand smoke. It is also reported that an increased tremor, startle reflex, or other problems in babies who have been exposed to cigarette smoke during gestation.

3) Marijuana - Marijuana can cause low birth weight, jitteriness, low blood sugar, intracranial bleeding, low levels of calcium in the blood, or sepsis (an infection of the blood). Marijuana during pregnancy can also cause other problems in the newborns, such as irritability, poor feeding, and rapid breathing.

4) Cocaine - The use of cocaine is also known to cause numerous complications during pregnancy, like fetal growth restriction, miscarriage, microcephaly, and problems with the development of the genital tract or urinary system. Children of mothers who use cocaine during gestation are also more likely to develop neurobehavioural problems. Cocaine abuse can also cause complications during pregnancy, called placental abruption.

What Precautions Should Be Taken to Avoid Birth Defects in Babies?

• It is good to provide the doctor with a list of all drugs taken, including prescriptions, nutrition supplements, over-the-counter medicines, and complementary therapies.

• Inform the healthcare professionals about habits like smoking, drinking alcohol, or taking illegal drugs, even if it is taken occasionally or socially.

• Ask for counseling if needed to quit smoking, alcohol, and other drugs.

• If any drugs are taken for chronic illness, they should not be stopped until suggested by the doctors. If needed, the doctors may alter the dose or medicine so that it will not cause any harm to the developing fetus.

• Consult a physician and take folic acid supplements before conception and during the first trimester of pregnancy because folic acid will reduce neural defects in babies.

Conclusion:

Drugs taken by mothers during pregnancy can cause birth defects in their offspring. However, drugs for some chronic illnesses should be continued even during pregnancy, or else they can cause more harm to the fetus. So it is important to provide all details of the drugs to the healthcare professional and discuss their effects on pregnancy.