Knowing exactly how far along you are in pregnancy can be confusing. Pregnancy symptoms are different for each woman and make for an unreliable guide to determine where you are in the gestational period. So exactly how does one determine their date of conception or due date?
When Was Your Last Period?
Knowing the first date of your last period is key. This is the date most commonly used to determine gestational age. For most women, this date is about two weeks before ovulation and conception occurred. Conception typically takes place between 11 and 21 days after the first day of your last period.
Most women don’t know their exact day of ovulation, but they usually know when their last period began, so this is the most reliable way to determine how far along you are and when you would be full term.
How Do I Calculate My Due Date?
To account for the two weeks prior to conception, doctors take the first day of your last menstrual period (LMP) and add 280 days (or 40 weeks) to determine the due date.
From there, you can also determine how far along you are by counting how many weeks it has been since the first day of your last period. For instance, if your last period began on August 1st, you would be eight weeks on September 26th, 13 weeks on October 31st, and your due date would be May 8th. This example is based on a 28-day cycle. If your cycle is longer or shorter, it will change slightly.
Using Ultrasound to Determine or Verify Gestational Age
Another way to determine or verify gestational age is through ultrasound. This is especially helpful for women who have irregular periods or who cannot recall the first day of their last period.
Gestational age can be measured using ultrasound as early as five or six weeks after your last menstrual period. Measuring in this way is most accurate during early pregnancy and is best done between the eighth and 18th weeks. Ultrasound is less accurate after this timeframe.
Ultrasounds performed during the first 12 weeks are considered to be accurate within three to five days, while those performed between 12 and 22 weeks are accurate within 10 days. Those done after 22 weeks cannot be used to determine gestational age, according to UltrasoundCare.com.
Come in for a Free Self-Pregnancy Test
If you are unsure whether you’re pregnant or if you’re facing an unplanned pregnancy and would like to discuss your options, come see us at Avail NYC. All our services are free of charge, and we are a safe, confidential place to think through your next steps.
We offer clients a free self-administered, urine pregnancy test and a free ultrasound by referral to a women’s medical clinic if the test is positive. Our client advocates also provide a linear decision-making tool which can help you explore your values and goals in the midst of your situation.
Make a free appointment today—our caring, non-judgmental team is here you to support you.
Avail NYC exists to be a safe haven for women and men facing an unexpected pregnancy or seeking support after an abortion. We are not a medical provider.