Pregnancy, also known as gestation occurs after sexual intercourse or assisted reproductive technology. There are numerous ways to test and check if the women is pregnant some of which are either based on the symptoms like morning sickness, missed menstrual periods, tiredness, back pain etc. while another way to test pregnancy is by using pregnancy tests. It is really important for a women to keep a check on the menstrual periods. Gestational age or the pregnancy age depends on the Last Menstrual Period (LMP). Pregnancy age can be determined by LMP or by more accurate methods available today such as obstetric ultrasonography. Pregnancy age can help the pregnant women as well as the family in various ways. Some of the methods of determining the age are: Last Menstrual Period: Gestation date can be easily calculated if the women know the first day of her last menstrual period. Gestation age does not depend on the date of conception but on the first day of the pregnant women’s last menstrual Period. This method can be difficult when the women are not sure about the first day of her last menstrual period. Ultrasound: After the mother’s last menstrual period, the pregnancy age can be determined as early as 5-6 weeks. Measuring the baby using ultrasound technique is most accurate and reliable in early pregnancy. Using this technique is most reliable when the pregnancy age is between 8th and 18th Sometimes this method fails to give accurate results as it depends on the baby’s growth which can be unusually small or big in some cases. Vitro fertilization: This is a method of fertilization of an egg with a sperm outside the body. This is also known as test tube baby and is a very useful method for infertility treatment. In this the fertilized egg is transferred back to the surrogate’s uterus. The age of the unborn can be determined using the age of the fertilized egg. Benefits of knowing Pregnancy age or Gestation age: This helps in finding out the estimated date of delivery by calculate pregnancy by due date. Estimating the time which a fetus can survive outside mother’s womb, depending upon maturity and environmental conditions. Birth classification (preterm, term, post-term) Estimating various risk factors after birth. Prescribing various medications and supplements based on child’s age and the ongoing pregnancy age. It can be helpful for various prenatal tests which can be helpful for detecting complications as early as possible in pregnancy. For scheduling regular checkups that help doctors to prevent health problems and helps in promoting a healthy lifestyle for both mother and child. Generally women always keep a check on the last menstrual period occurred but sometimes she might skip the dates so in such cases LMP can be checked by the other options available. Once the Estimated due date (EDD) is calculated using any of the above methods, it is hardly changed but exceptions can always be there.Various online applications are easily available for checking the Pregnancy due date calculator week by week.