Frequently Asked Questions

15 common questions on pregnancy dating, the 3 modes, twins, and visit schedules.

Q1. From when is gestational age counted?

From the first day of your last menstrual period (LMP), not conception. Since ovulation/conception typically occurs ~14 days after LMP, fetal age is approximately GA − 2 weeks.

Q2. What if I do not remember my LMP?

Use the Ovulation mode if you tracked ovulation (LH kit/BBT): ovulation + 266 days. If neither is available, the Ultrasound mode is most accurate — first-trimester CRL gives ±5–7 days.

Q3. Is the Naegele rule accurate?

It assumes a 28-day cycle. Shorter or longer cycles introduce error, so first-trimester ultrasound is used to refine the date. Most deliveries occur within EDD ± 2 weeks.

Q4. My cycles are irregular — is the LMP mode still valid?

It gives a rough estimate but ultrasound confirmation is recommended. Late ovulation means the true GA is lower than the LMP-based value.

Q5. LMP and ultrasound dates disagree — which should I trust?

If they disagree by more than 7 days, obstetricians typically re-date to the ultrasound (CRL is most reliable in the first trimester). Follow your OB/GYN’s judgment.

Q6. Do twins/multiples use the same calculation?

The EDD formula is the same, but twins have higher preterm risk and often deliver at 36–38w. This calculator is tuned for singleton pregnancies.

Q7. What do 24w, 37w, and 40w mean?

24w = age of viability, 37w = start of full term, 39w 0d – 40w 6d = optimal delivery window, 42w = post-term threshold.

Q8. What defines preterm birth?

Any birth before 37w 0d is preterm. <28w = extremely preterm, 28–32w = very preterm, 32–34w = moderately preterm, 34–37w = late preterm.

Q9. How is the progress bar calculated?

Days elapsed since LMP divided by 280 (40w 0d). It caps at 100% at 40w; overdue days are shown separately as D+.

Q10. Are the fruit size comparisons scientifically sourced?

We use widely-cited ACOG/Mayo Clinic/NHS population averages for length and weight, then match them to commonly-used fruit/vegetable comparisons. Individual babies vary significantly.

Q11. How do I use the ICS calendar file?

Open the downloaded .ics file in Google Calendar (Import) or Apple Calendar (double-click) and the 11 recommended visits appear as all-day events. Confirm the exact dates with your clinic.

Q12. When and how much folic acid should I take?

400–800 mcg daily from pre-conception through at least 12 weeks is standard. A history of neural-tube defects may require 4 mg under medical supervision.

Q13. When will I feel fetal movement?

First-time pregnancies typically feel movement at 18–22w; subsequent pregnancies at 16–20w. After 28w, many clinicians recommend counting 10 kicks per 2 hours.

Q14. Is the share image safe to post?

The PNG contains no personal identifiers — only gestational weeks and due date. It is safe for social sharing, but the choice of audience is yours since pregnancy is private health information.

Q15. Is this site medical advice?

No. This tool provides estimates only and does not replace diagnosis or medical care. Always consult your OB/GYN for accurate assessments.