If you’ve ever volunteered at our Center, taken a tour or even dropped by and chatted with someone from the nursing staff, then chances are you’ve probably seen the Pale Yellow pregnancy dating wheel. It’s something that we use for quick, probable dating based on a women’s last menstrual period. In and of itself, pregnancy dating can be confusing but most women want to know exactly how far along they are even before they see their OB-GYN.                                                                                                                                                                         

Medical professionals use two terms, gestational age and fertilization age, to talk about the age of the baby. Most women ovulate in the middle of their monthly cycle, typically around the 14th day after the last period began.  Conception (sperm meeting the egg) usually occurs around this date, two weeks after the last menstrual period. Gestational age is the term most used at the doctor’s office, pregnancy center, or abortion clinic.  This age includes the two weeks before the fertilization of the egg by the sperm.  According to the term gestational age, the first day of your last menstrual period is considered the beginning of your pregnancy, even though the baby is not conceived until the 2nd week by this dating.  Fertilization age, on the other hand, does not include the time between your last period date and the time of conception.  Fertilization age may make more sense to you when you think about the date you got pregnant.  For example, a baby that is 7 weeks gestational age is only 5 weeks fertilization age.

And there you have it.

Now you know the medical language used to help a woman find her date of conception and probable due date.