Small for Gestational Age

What is gestational age?

Gestational age refers to how many weeks the fetus has been growing inside the mother's womb. It is based on the date of the mother's last menstrual period. An ultrasound during the first 3 months of pregnancy measuring the head, abdomen, and thigh bone also helps to determine gestational age.

Most babies are born between 38 and 42 weeks of gestation. Right after birth, your doctor checks your child's weight and length, and compares it with the weight and length expected for his or her gestational age. Most babies have a birth length and weight very close to what is expected, but some are larger or heavier than expected, and some are smaller or lighter.

Your doctor may also have looked at other things, such as your baby's head size, the condition of skin and hair, reflexes, muscle tone, posture, and other signs to determine your baby's developmental gestational age. The gestational age describes the age that your baby actually looks and acts. For example, although your baby may have been born after 39 weeks, he or she may look and act more like a baby born after only 35 weeks.


Small for Gestational Age

Some children are born small for gestational age (SGA), and most of the time it is not known why. It just happens. When a cause can be determined, the three most common reasons are issues with the fetus, including a multiple birth (twins, triplets, etc.) or genetic defect; problems with the placenta that do not let the fetus get enough nutrients; or mother's health issues such as heart disease or malnutrition, or drug, alcohol, or cigarette abuse.

Children born SGA may have a normal amount of growth hormone, or they may have less growth hormone than the average child.

Most babies born SGA catch up to normal size and height during the first year with catch-up growth nearing completion by age 2. In some cases, infants who are born SGA will remain well below average height throughout their lives.

This content is for informational purposes only, and is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified healthcare professional with any questions you may have regarding a medical condition.