The size of a baby in the womb at 18 weeks is not the same for all pregnancies. Babies develop at different rates in the womb, just as they do after birth. Different medical experts present different weights and measurements for a baby in the womb at 18 weeks, so use the standards as a guideline to give you a general idea of how big your baby is.
Weight
The Mayo Clinic lists the weight of a baby in the womb at 18 weeks as about 7 oz. The American Pregnancy Association says the baby weighs approximately 5.5 oz., and Pregnancy.org, gives the weight as about 6.7 oz.
Length
A baby in the womb at 18 weeks measures from 5.5 to 6.29 in. long, measured from crown to rump. Baby Center, a pregnancy and parenting information website, describes the size of a baby at this stage of pregnancy as "about the length of a bell pepper."
Considerations
By the 18th week of pregnancy, your baby's bones begin to harden, his fingerprints are almost complete and his ears begin to function. Loud noises may startle your baby now, and he can hear you sing to him. His eyes continue to develop and are now sensitive to light.
Features
Your baby's sex organs are in place by week 18 of your pregnancy. If the baby cooperates, an ultrasound may now detect the baby's sex.
Effects
At 18 weeks of pregnancy, your baby can flex her arms and legs. She now has eyebrows and eyelashes and she can swallow. Her kidneys begin to function and produce urine.
