The causes of intrauterine growth restriction (IUGR) relate to problems that keep cells from growing properly, or making them become smaller. An oxygen restriction and lack of the nutrients required for normal development may be one source. Infection is another. If parents are small, their baby may be small, but this relates to genetics and is not a cause of intrauterine growth restriction.
A number of risk factors for IUGR, include conditions affecting health of the mother, the fetus and the reproductive system.
Some of the conditions affecting the mother that cause intrauterine growth restriction involve lifestyle choices such as cigarette smoking, excessive use of alcohol and drug abuse. Poor nutrition also plays a role. Health problems related to IUGR include:
- high blood pressure or heart disease
- respiratory disease
- kidney disease
- advanced diabetes
Several causes of IUGR arise from risks to the baby, such as being a twin or triplet, having developed an infection, congenital abnormalities (birth defects) and chromosomal abnormalities.
Reproductive System Risks
Several problems with the placenta and uterus are noted as possible causes of intrauterine growth restriction. The placenta may attach itself incorrectly low in the uterus, or detach from the uterus. Other factors include reduced blood flow and infections in the placenta and uterus.
A maternal disease, chromosomal abnormalities or problems with the placenta are usually the cause of an early onset of IUGR (in the first 32 weeks of pregnancy). After that period, other problems are usually the causes of IUGR.