A pregnancy is a time of joy, excitement, emotional and physical change and anticipation for most women. It is one of those great miracles of life.

Once a woman has found out that she is pregnant and if the news is a welcome one, the next question is her mind probably is – “When is the baby due?” Most doctors calculate a due date and you too can use a pregnancy due date calculator to determine the date of the big day. You can find a due date calculator online but you need to understand that the calculation only gives an approximate date which is what your doctor gives you as well.

The system to calculate delivery dates was first determined by a doctor by the name Naegele in the mid 1900s. His studies showed him that most babies were born approximately 266 days after conception. He also determined that conception generally occurred about 14 days after the start of a woman’s menstrual cycle. Talking these two factors into consideration the date is about 40 weeks after the start of the woman’s last period.

This system of calculating due is only an approximation method. The actual date of delivery varies from woman to woman due to a variety of personal factors like age, hormonal balance, etc. Health plays a very important role in determining the term of the pregnancy and the delivery date. A normal pregnancy can last from anywhere between 37 to 42 weeks and very few women deliver on the calculated date. In fact, only 4% of births occur on their due date, 6 to 10% of babies are born early and 4 to14% of babies are born after 42 weeks. Aside form all the statistics the due date calculator that Dr. Naegele came up with still gives the best estimate and is still in use today.

The due date can be corrected after the ultrasound during the first trimester. During this ultrasound the size of the baby is measured and the delivery date is altered. You can also find out the sex of the baby during the ultrasound if you desire. But even the date to date calculator does not give an exact delivery date because there are a number of factors that could triggers labor. Once you reach the 40 week period of your pregnancy, your doctor will ask you to begin weekly or bi-weekly stress tests to make sure that your baby is still safe in the womb. Labor is induced if it is determined that the baby is in distress or any other problems are discovered.