How do environmental factors like infection and drugs affect birth defects?

How do environmental factors like infection and drugs affect birth defects?

Environmental factors can increase the risk of miscarriage, birth defects, or they might have no effect on your baby at all, depending on at what point during the pregnancy the exposure occurs.

Your developing baby goes through two major stages of development after conception. The first, or embryo stage, occurs during the first 10 weeks after conception. Most of the major body systems and organs form during this time. The second, or fetal stage, is the remainder of the pregnancy. This fetal period is a time of growth of the organs and of the fetus in general. Your developing baby is most vulnerable to injury during the embryo stage when organs are developing. Indeed, infections and drugs can cause the greatest damage when exposure occurs two to 10 weeks after conception.

Diabetes and obesity can possibly increase your child’s risk of birth defects. Your healthcare provider may suggest that you do your best to manage these conditions before you get pregnant.

Some medicines and recreational drugs can cause birth defects, which are most severe when used during the first three months of pregnancy. Thalidomide, an anti-nausea medicine prescribed during the 1960s, caused birth defects called phocomelia (absence of most of the arm with the hands extending flipper-like from the shoulders).

There’s also isotretinoin, previously known as Accutane or Roaccutane. Isotretinoin is a retinoid, a man-made form of vitamin A that’s used to treat skin conditions. It causes fetal retinoid syndrome. Characteristics of fetal retinoid syndrome may include:

• Growth delay.
• Malformations of the skull and face.
• Abnormalities of the central nervous system.
• Abnormalities of the heart.
• Abnormalities of the parathyroid gland.
• Abnormalities of the renal, thymus gland.

Alcohol is the most commonly used drug that causes birth defects. Fetal alcohol syndrome is a term used to describe the typical birth defects caused by the mother’s alcohol use:

• Learning disabilities.
• Developmental delay.
• Irritability.
• Hyperactivity.
• Poor coordination.
• Abnormalities of facial features.

Another environmental factor that can cause birth defects is uterine constraint. The fetus grows in the mother’s uterus and is surrounded by amniotic fluid (similar to being suspended in a bag of water) that cushions it from excessive pressure. If the sack of fibers that holds the fluid breaks, bands of fibers from the torn sack can press on the fetus and cause amniotic band syndrome (which can result in partial contraction of or amputation of an arm or leg). An inadequate amount of amniotic fluid can cause excessive pressure on the entire baby, causing pulmonary hypoplasia (lack of development of the lungs).

Medical science has identified the cause of about 30% of birth defects. That means about 70% remain without a straightforward cause. As many as 50-70% of birth defects are sporadic, and their cause remains unknown. A combination of environmental and genetic factors can increase the risk of certain birth defects.