What is my gestational age given a positive pregnancy test and last menstrual period (LMP) on March 31, 2025?

From the Guidelines

You are approximately 4-5 weeks pregnant based on your last menstrual period (LMP) date of March 31,2025. Pregnancy dating is typically calculated from the first day of your last menstrual period, even though conception usually occurs about 2 weeks later 1. If today's date is May 12,2025, and considering a regular 28-day menstrual cycle, you would be around 4-5 weeks pregnant. However, it's essential to note that home pregnancy tests detect the hormone human chorionic gonadotropin (hCG) in your urine, which begins to be produced after a fertilized egg implants in the uterus, usually 6-12 days after conception.

• A positive test confirms pregnancy, but the exact dating would need to be verified by a healthcare provider through an ultrasound, which can provide a more accurate estimate of gestational age, especially when using crown-rump length (CRL) measurements in early pregnancy 1.
• I recommend scheduling an appointment with your healthcare provider as soon as possible to confirm your pregnancy, establish accurate dating, begin prenatal care, and start prenatal vitamins containing folic acid if you haven't already.
• It's crucial to prioritize prenatal care to ensure the best possible outcomes for both you and your baby, focusing on minimizing morbidity, mortality, and optimizing quality of life 1.

From the Research

Pregnancy Duration Calculation

To determine how pregnant you are, we need to calculate the gestational age based on your last period.

• Last period: 3/31/25
• Assuming a regular 28-day menstrual cycle, ovulation typically occurs around 14 days after the start of the last period.
• Fertilization usually happens within 24 hours of ovulation.
• Given that a positive pregnancy test is typically possible 3-4 weeks after the last period, we can estimate the gestational age.

Estimated Gestational Age

Based on the provided information, it is approximately 4 weeks since your last period.

• Gestational age is usually calculated from the first day of the last menstrual period (LMP).
• Considering this, you are likely around 4 weeks pregnant 2.

Important Considerations

While calculating the gestational age, it's essential to note that every pregnancy is unique, and the exact gestational age may vary.

• Factors such as irregular menstrual cycles or fertilization timing can influence the accuracy of gestational age calculations.
• It's crucial to consult a healthcare provider for a more accurate assessment and to discuss any concerns or questions you may have about your pregnancy 3, 4, 5, 6.