Your Baby's Weight
In the first trimester, the average weight of your fetus should be between ½ ounce and one ounce.
This jumps drastically in the second trimester when your baby begins to gain weight much faster.
By the end of the fourth month your child should be approximately four times heavier than the first trimester. Four ounces by the end of the fourth month is common.
By the end of the fifth month, the fetus generally has grown to ¾ pounds and by the end of the sixth month the weight should have grown to between 1 1/4 pounds and 1 ½ pounds.
Fetal growth in the third trimester further increases as your child develops the necessary fat to survive outside the womb and as his or her internal organs get bigger.
Around 28 weeks, the seventh month and 26 weeks after conception, your baby should be around two to 2 ½ pounds and is approximately 10 inches long.
Survival rate with fewer complications if born at this stage is high at about 90 percent. A full term healthy baby at 40 weeks gestation should typically be at least 14 inches long and weigh about 7 ½ pounds.
Possible Reasons for Fetal Growth Restriction
If your doctor or midwife decides that your baby isn't growing as quickly as she should, the practitioner may check into possible causes.
Fetal growth retardation can be caused when something is wrong with the placenta, if the mother is experiencing preeclamsia or hypertension, fetal chromosomal abnormalities, atmosphere influences like air pollution or smoking, or a chronic health condition of the mother like diabetes or sickle cell anemia.
All these factors can reduce the amount of oxygen reaching the baby and slow growth.