Most pregnant women are confused about the terms "gestational age" and "fetal age". You might be wondering whether these terms mean one and the same thing. The information provided below might help you understand your ultra-sound reports and calculation of your due date. Gestational Age This is the time measured from the first day of your last menstrual period (LMP) to the current date. It is usually expressed in weeks, and you can cross-check week-by-week symptoms of pregnancy after knowing the age. A full term pregnancy involves development of fetus over about 40 weeks (about 280 days). Childbirth during 38-40 weeks of pregnancy is considered as normal, but a baby born before 37 weeks is considered as "premature". Human gestation period can be anywhere between 259 to 294 days. During pregnancy, doctors check whether the size of the head, abdomen, thigh bone, etc. is correct according to the gestational age. They do it with the help of ultra sound tests. Fetal Age The most fertile time to get pregnant is near ovulation. When the male sperm fertilizes the egg released by your ovaries, you can say that you have conceived. Ovaries release the female egg, and the egg is available for fertilization only for 24 hours. If you have sex on that day, then the chances of getting pregnant are maximum. Fetal age is counted not from the date of last menstrual cycle, but from the date of conception. In case you don't know the exact date of conception, doctors can estimate the date of conception from simple calculations. Normally, menstruation starts 14 days after ovulation. Ovulation and conception usually takes place in the middle of the menstrual cycle (if the cycle lasts for 28 days). So, fetal age is normally two weeks less than the gestational age. Why Age Calculation is Essential After the birth of the baby, assessment of weight, length, head circumference, skin, and hair condition of the newborn baby helps decide the gestational age; which in turn helps determine whether the newborn baby needs any special care. Doctors can estimate the age by checking the reflexes, muscle tone, posture, and vital signs of the infant. During pregnancy, knowing the gestational and fetal age helps determine the course of the treatment for the baby, especially in case of expected or potential problems. During prenatal checkups, development of the uterus and the fetus is monitored. Only after knowing the age of the fetus, a doctor can confirm that the development is perfect, and there won't be any problem during childbirth. The doctor can check the accuracy of the due date only after knowing the age of the fetus. For 7 weeks gestation, fetal age would be 5 weeks. On Internet, due date calculators, fetal/gestational age calculators are readily available. You just have to feed the date of your last menstrual period and average length of your cycle. Knowing the age of the fetus helps know whether the development of the fetus is normal. Mothers feel relaxed when they know that their baby is growing at the correct rate, she is gaining weight according to the established standards, and the organs are developing at the right time. Disclaimer: This Buzzle article is for informative purposes only, and should not be used as a replacement for expert medical advice.