Pregnancy Due Date Calculator

Due dates are estimates, not guarantees. Only about 5% of babies are born exactly on their calculated due date. Most healthy pregnancies deliver between 37 and 42 weeks. The LMP method assumes a regular 28-day cycle with ovulation on day 14, but many women have different cycle lengths or irregular periods, which can affect accuracy. Early ultrasounds (before 20 weeks) can provide more accurate dating, often within 5-7 days. If your cycles are irregular or you're unsure of your LMP, discuss dating with your healthcare provider, who may adjust your due date based on ultrasound measurements. Remember that a due date is a general guideline, not a deadline, and healthy babies come when they're ready.

Gestational age and fetal age are two different ways of measuring pregnancy duration, which often causes confusion:

• Gestational age is measured from the first day of your last menstrual period (LMP) and is the standard clinical measurement used by most healthcare providers. It's approximately 2 weeks longer than fetal age.
• Fetal age (or embryonic age) refers to the actual time since conception/fertilization occurred, which typically happens about 2 weeks after the start of your last period.

For example, when a doctor says you're "8 weeks pregnant" using gestational age, the embryo has actually been developing for about 6 weeks. This calculator uses gestational age, the standard medical convention, for all calculations and timelines.

Yes, cycle length can affect due date accuracy when using the LMP method. The standard calculation assumes a 28-day cycle with ovulation on day 14, but many women have different patterns. If you have longer cycles (e.g., 35 days), you likely ovulate later, and your due date may be later than calculated. Conversely, with shorter cycles (e.g., 21 days), you may ovulate earlier, making your due date earlier than calculated. For more accurate dating with irregular or non-28-day cycles: (1) Use the conception date method if you tracked ovulation; (2) Consider adjusting the date (e.g., for a 35-day cycle, add approximately 7 days to the due date); (3) Discuss with your healthcare provider, who may recommend an early dating ultrasound for more precision.

Most healthcare providers recommend scheduling your first prenatal visit as soon as you confirm your pregnancy, typically between weeks 6-10 of pregnancy (counting from the first day of your last period). However, timing can vary based on: (1) Your health history - earlier visits may be recommended if you have pre-existing conditions or pregnancy complications; (2) Provider preferences - some may want to see you earlier, others later; (3) Age and risk factors - women over 35 or with high-risk factors may be seen earlier. The first visit is usually the longest and most comprehensive, including medical history review, physical examination, blood tests, possibly an ultrasound, and discussion of your care plan. Don't delay contacting your provider once you know you're pregnant, as they can advise on the appropriate timing for your specific situation.

Going past your due date is common - about 30% of pregnancies continue beyond week 40. If your pregnancy extends beyond your due date, here's what typically happens:

• 40-41 weeks: Increased monitoring through more frequent prenatal visits, non-stress tests, and amniotic fluid checks to ensure the baby is healthy.
• 41-42 weeks: Your provider may discuss induction options as the risks of complications start to increase slightly after 41 weeks.
• Beyond 42 weeks: Most healthcare providers recommend delivery by 42 weeks, as risks increase more significantly past this point.

Your provider's approach will depend on your health, the baby's condition, your previous pregnancy history, and your personal preferences. Some may suggest membrane sweeping or natural induction methods before medical induction. Throughout this time, stay attentive to fetal movements and report any decrease in activity to your healthcare provider immediately.