Once a woman has passed her first trimester of pregnancy, the doctor will begin closer tracking of the infant's fetal growth. Fetal growth is the distance from the top of the uterus to the pubic bone and is measured in centimeters. This is also called fundal height and the fundal height generally matches the number of weeks a women is in her pregnancy. For example, if a woman is in her 23rd week of pregnancy, her fundal height should be within 3 - 4 centimeters of 23 cm.

Measure Fetal Growth

1. Measure the uterus. A tape measure is used to measure the length of the "baby bump". The doctor feels on the mother's belly for the top of the uterus and measures from there to the pubic bone.
The measurement is taken within 3 weeks of the gestational age, between 20 and 38 weeks of gestation. A fundal height that varies by more than 3 cm (1.18 inches) may signal a problem.
A lag of 4 cm (1.58 inches) or more from the number of gestational weeks may suggest growth restriction. Your doctor will consult with you if there is any question about the baby's growth.
There is an error potential of about 1 week up to 20 gestational weeks, 2 weeks from 20 to 36 weeks of gestation, and approximately 3 weeks thereafter.

2. Use ultrasound technology to help determine possible abnormalities and to confirm gestational age.
This is a procedure that uses high-frequency sound waves to scan the abdomen and pelvic area using highly technical equipment. This creates a picture (sonogram) of the fetus and placenta. It is completely safe and allows doctors to detect problems in early stages.
Images from these are generally 2-D, but new 3D technology is quickly emerging, allowing doctors a fuller, more accurate view. Frequent ultrasounds are not recommended for normal pregnancies.