Perinatal Substance Exposure - A Run-Through of Side Effects

Introduction:

The growth of the fetus takes place in a protected environment in the womb. The sac into which the growth and development of the fetus take place is known as the placenta. The placenta does not only protect the fetus, but it also helps to supply nutrients to the fetus. These substances, along with oxygen, reach the fetus via placental circulation. Along with the nutrients, toxic substances may also reach the fetus. Exposure to toxic substances may cause irreversible damage to the growing baby. Understanding the potentially harmful effects of these substances is necessary for a safe pregnancy.

What Are the Toxic Substances?

Many toxic substances are potentially harmful to the fetus. But substances like alcohol, cannabis, drugs, and opioids cause more damage to the embryo. These substances affect cellular, chemical, and physiological functional changes and are responsible for fetal damage. Even smoking from various sources may cause fatal damage.

What Is the Effect of Smoking?

Smoking is very common among pregnant women in the form of cigarettes, electronic cigarettes, and smokeless tobacco. Passive smoking is also a matter of concern for pregnancy. Tobacco and smoke contain toxic substances like hydrogen cyanide, polycyclic, aromatic hydrocarbons, carbon monoxide, and nitrogen oxides. These substances are harmful to the female reproductive system. The effect of these substances on the female reproductive system are:

1. Impaired ovulation (egg production).

2. Problem regarding tubal transport (passage of the embryo in the fallopian tube) and embryo implantation.

3. Impaired pre-implantation development of the embryo.

As evident, smoking is injurious to the pregnancy even in the early stages. These terrible effects can even be seen at later stages of embryonic development. The effect of smoking on the fetus are:

1. Carbon monoxide binds strongly with the fetal blood, and its elimination is slower than mother. This causes reduced oxygen delivery to fetal tissue. As a result, brain and nerve tissue growth is impaired.

2. Nicotine is responsible for hormonal imbalance and increased secretion of noradrenaline and adrenaline. This causes an increase in fetal heart rate. These hormones also cause constriction of the blood vessels supplying the uterus and thus decreasing the blood supply and oxygen to the fetus. Thus maternal and fetal blood pressure is altered.

3. Cadmium is responsible for the impaired functioning of enzymes like placental alkaline phosphatase.

What Is the Effect of Alcohol?

Alcohol is another substance that can affect fetal growth and development. In the United States, around 15 % of pregnant women consume alcohol. Alcohol produces toxic substances like acetaldehydes and reactive oxygen species (ROS) during metabolism. These substances are responsible for several severe conditions, collectively known as fetal alcohol spectrum disorders (FASD) or fetal alcohol syndrome (FAS). The clinical manifestations of this conditions are:

The growth of the child is hampered. Often, they are underdeveloped and underweight. Many facial anomalies can be observed in the child, and these are:

• Flattened nasal bridge.

• Thin upper lip.

• Absence or excessive elongation of philtrum (a vertical groove between the nose's base and the upper lip's border).

• Reduced opening between the two eyelids (palpebral fissure).

White matter deficits in the brain and its abnormal integrity, especially in the corpus callosum (a portion of the brain that connects the left and right cerebral hemispheres), are found in this condition. Delayed motor and speech development and hearing impairment. The cognitive development of the child is poor with poor IQ (intelligence quotient).

What Is the Effect of Cannabis on Pregnancy?

One of the most commonly used illicit substances during pregnancy and lactation is cannabis. Cannabis can be taken in various forms, like weed and marijuana, which are responsible for producing cannabinoids. These are absorbed by the lungs when smoked or from the gastrointestinal tract when ingested and are responsible for medicinal and psychoactive properties. Tetrahydrocannabinol (THC) is a small and highly lipophilic metabolic product of cannabinoids which are rapid to the brain and fat. This substance may cross the placental barrier and can be found in fetal plasma. The effect of cannabis on pregnancy are:

1. Impaired muscle contraction and relaxation of the fallopian tube are responsible for the impairment of fallopian motility.

2. Cannabis addiction has been associated with ectopic pregnancy (egg implantation outside the uterus).

3. Folic acid is essential for embryonic development. Tetrahydrocannabinol (THC) causes decreased folic acid uptake in the body and is responsible for miscarriage.

4. Cannabinoids act on CB1 receptors in the uterus and halt the development of blastocysts.

What Is the Effect of Cannabis on Embryos?

The effect of cannabis on embryos are:

1. As Tetrahydrocannabinol (THC) is responsible for low folic acid uptake, it causes the child's neural tube defects and low birth weight.

2. The cellular growth of the embryos is impaired, and malformation in new blood vessel formation can also be seen.

3. The head circumference of the child is less.

4. Cognitive development is slow with the low IQ of the baby.

What Are the Effects of Drugs and Opioids?

Cocaines prevent the reuptake of catecholamines presynaptically, increasing these neurotransmitter levels. As a result of which, maternal blood pressure increases. This causes vasoconstriction and tachycardia (increased heart rate), decreasing uterine and placental blood flow. This causes less oxygenation to the fetus and the development of hypoxic conditions. Methamphetamine is a synthetic stimulant and illicit drug. This is the most commonly used drug in pregnancy. Like cocaine, Methamphetamine also causes inhibition in the action of neurotransmitters like serotonin, norepinephrine, and dopamine. This causes impaired functioning of the amniotic fluid and fetal circulation. As a result, constriction of the placental blood vessels and hypertension may happen. The side effects of these drugs are:

1. Delayed and abnormal neural growth of the fetus. Delayed growth of sensory and motor functioning.

2. Premature labor.

3. Low birth weight.

4. The sudden death of the fetus in the placenta.

What Are the Side Effects of Opioids and Other Drugs During Pregnancy?

Opioids and heroin are other drugs that can be harmful in pregnancy and cause fetal developmental problems. Even opioid drugs like Buprenorphine may cross placental barriers. These substances bind to the specific proteins in the brain and are responsible for pleasure sensations. This sudden stoppage results in withdrawal symptoms like seizures and a sudden rise in blood pressure. Even in neonates, it may cause neonatal abstinence syndrome. Such a condition can be treated by opioid replacement therapy with long-acting opioids such as Methadone and Buprenorphine. Other than this, increased breastfeeding, behavior training, and frequent food supplement can be used to treat this condition. This condition is characterized by the following:

• High-pitched excessive cry.

• Poor sleep, abnormal behavior.

• Excessive sweating, sneezing, and seizures.

Conclusion:

Exposure to toxic substances can harm both mother and child. Permanent damage to growth and development may happen due to such exposure. Counseling before and during the pregnancy can be helpful in such cases to keep the mother away from all these substances. Community help and support from caregivers are also needed. Examining nail and hair samples is necessary to monitor drug intake.