Just how pregnant ARE you?

Not sure just how far along you are with your pregnancy?? Join the club! Many women, for a wide variety of reasons, just aren't sure when they got pregnant or what their due date might be.
Calculating Gestational Age:
Last Menstrual Period: If the mother has a regular period and knows the first day of her last menstrual period, gestational age can be calculated from this date. Gestational age is calculated from the first day of the mother's last menstrual period and not from the date of conception.
Ultrasound: The baby can be measured as early as 5 or 6 weeks after the mother's last menstrual period. Measuring the baby using ultrasound is most accurate in early pregnancy. It becomes less accurate later in pregnancy. The best time to estimate gestational age using ultrasound is between the 8th and 18th weeks of pregnancy. The most accurate way to determine gestational age is using the first day of the woman's last menstrual period and confirming this gestational age with the measurement from an ultrasound exam.
Calculating Conception Date:
In a Typical Pregnancy: For a woman with a regular period, conception typically occurs about 11-21 days after the first day of the last period. Most women do not know the exact date of conception, and their conception date is merely an estimate based on the first day of their last period.
Special Cases: Women who undergo special procedures such as artificial insemination or in vitro fertilization typically know the exact date of conception.
Calculating Due Date:
Estimated Due Date: Based on the last menstrual period, the estimated due date is 40 weeks from the first day of the period. This is just an estimate since only about 5% of babies are born on their estimated due date.
Difficulties in Determining Gestational Age:
Last Menstrual Period: For women who have irregular menstrual periods or women who cannot remember the first day of their last menstrual period, it can be difficult to determine gestational age using this method. In these cases, an ultrasound exam is often required to determine gestational age.
Baby's Growth: In some cases it is difficult to determine the gestational age because the baby is unusually large or small. Also, in some cases the size of the uterus in early pregnancy or the height of the uterus in later pregnancy does not match the first day of the last menstrual period. In these cases as well, it is difficult to obtain an accurate gestational age.

My recommendation (as a mother, not an MD) are to assume you'll probabl have your baby about 8 and 1/2 months after you discovered you were pregnant, give or take a week. Enjoy your pregnancy and take this opportunity to do all the healthy things for yourself that you've been meaning to do for a long time:

Stop smoking immediately!
Walk and do slow stretches daily
Eat your fruits and veggies
Limit your sugar intake
Drink lots of pure water
Develop a spiritual practice of some kind...you don't have to go to church to be spiritual...something like quiet meditation on your blessings and your growing child would be lovely and calming!

Let me know if you have questions or comments!