Question 1

How is a pregnancy due date calculated?

Accepted Answer

The most common method is Naegele's Rule: Due Date = Last Menstrual Period (LMP) + 280 days (40 weeks). Equivalently: LMP + 9 months + 7 days. Example: LMP = January 15, 2025 → Due Date = October 22, 2025. Gestational age is counted from the LMP, not conception — this is why you are considered "2 weeks pregnant" at the time of conception (ovulation typically occurs around day 14 of the cycle). If conception date is known, add 266 days (38 weeks) to it. Ultrasound measurements in the first trimester (crown-rump length at 8–12 weeks) are considered the most accurate due date confirmation.

Question 2

How accurate is a pregnancy due date?

Accepted Answer

Only about 5% of babies are born on their exact due date. Approximately 80% of births occur within 2 weeks before or after the due date (between weeks 38–42). The due date is best understood as the midpoint of a 5-week window, not a precise delivery date. First-trimester ultrasound (8–13 weeks) predicts delivery within ±5–7 days. Second-trimester ultrasound is less accurate (±2–3 weeks). Factors affecting timing: first pregnancies tend to run 1–3 days longer, induction policies vary by provider, and twins and multiples typically arrive earlier (average ~36–37 weeks).

Question 3

When do the trimesters start and end?

Accepted Answer

Pregnancy is divided into three trimesters: First trimester: Weeks 1–13 (conception through end of month 3). Key events: implantation, major organ formation, risk of miscarriage is highest (10–20% of known pregnancies). Second trimester: Weeks 14–27 (months 4–6). Often called the "honeymoon trimester" — nausea typically subsides, baby movements felt ("quickening"). Third trimester: Weeks 28–40+ (months 7–9+). Baby gains weight rapidly; lungs mature; Braxton Hicks contractions begin. "Full term" is 39–40 weeks; "early term" is 37–38 weeks; "late term" is 41 weeks; "post-term" is 42+ weeks.

Question 4

What prenatal appointments should I schedule?

Accepted Answer

Standard prenatal care schedule (US): First visit at 8–10 weeks (confirm pregnancy, blood work, genetic counseling). Weeks 10–12: optional first-trimester screening (NIPT blood test, nuchal translucency ultrasound). Weeks 11–13: first-trimester ultrasound (due date confirmation, chromosomal abnormalities). Weeks 18–20: anatomy ultrasound (detailed organ scan, often when sex is revealed). Week 24–28: glucose tolerance test (gestational diabetes screening). Weeks 28–36: biweekly visits. Weeks 36–40: weekly visits. Group B Strep test at 35–37 weeks. Most women have 10–15 prenatal appointments total in an uncomplicated pregnancy.

Question 5

What are the earliest signs of pregnancy?

Accepted Answer

Early pregnancy symptoms (before a missed period or in the first few weeks): Implantation bleeding (light spotting around days 10–14 post-conception). Breast tenderness or fullness (caused by rising hCG and progesterone). Fatigue (progesterone levels rise dramatically). Mild cramping (uterus begins to expand). Nausea ("morning sickness" — though it can occur any time of day; typically starts around week 6). Frequent urination (kidneys begin filtering more blood). Heightened sense of smell. Positive home pregnancy test (most reliable after the first missed period; some tests detect hCG 5–6 days before missed period).

Question 6

What is gestational age vs fetal age?

Accepted Answer

Gestational age (GA) is counted from the first day of your Last Menstrual Period (LMP) — the standard used by all OBs, midwives, and ultrasound. At conception (typically day 14), gestational age is already 2 weeks. Fetal age (or embryonic age) is counted from actual conception — it is always approximately 2 weeks less than gestational age. When a doctor says "you are 8 weeks pregnant," the embryo is about 6 weeks old developmentally. All pregnancy milestones, due dates, and screening windows use gestational age. This explains why full-term pregnancy is "40 weeks" of gestational age but only ~38 weeks of actual fetal development.

Question 7

When can I find out the sex of the baby?

Accepted Answer

There are several timing options for determining fetal sex: NIPT blood test (Non-Invasive Prenatal Testing): as early as 9–10 weeks of pregnancy with 99%+ accuracy. This blood test screens for chromosomal conditions and can reveal sex. Chorionic Villus Sampling (CVS): 10–13 weeks, invasive test, near 100% accuracy but has miscarriage risk (done for medical reasons, not sex determination alone). Anatomy ultrasound: 18–20 weeks, approximately 95–99% accurate when baby is in a cooperative position. Early gender ultrasound: some practices offer 14–16 week ultrasound; 80–90% accurate. Home methods (skull theory, Ramzi method) have no scientific validity.

Question 8

What foods should be avoided during pregnancy?

Accepted Answer

Foods to avoid during pregnancy (FDA/ACOG guidelines): Raw or undercooked meat, poultry, and eggs (risk of Listeria, Salmonella, Toxoplasma). Raw oysters and shellfish (Vibrio bacteria). High-mercury fish: shark, swordfish, king mackerel, tilefish, bigeye tuna — limit to 2–3 servings/week of low-mercury fish (salmon, shrimp, catfish). Unpasteurized dairy products and soft cheeses (Brie, queso fresco, feta). Deli meats and hot dogs unless heated until steaming (Listeria risk). Raw sprouts. Alcohol (no safe level established). Caffeine: limit to under 200 mg/day (about one 12-oz cup of coffee). Unwashed produce.

Pregnancy Due Date Calculator

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How Pregnancy Due Dates Are Calculated

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Pregnancy Calculator — Frequently Asked Questions

How is a pregnancy due date calculated?

How accurate is a pregnancy due date?

When do the trimesters start and end?

What prenatal appointments should I schedule?

What are the earliest signs of pregnancy?

What is gestational age vs fetal age?

When can I find out the sex of the baby?

What foods should be avoided during pregnancy?

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Pregnancy Due Date Calculator

Pregnancy Details

Enter your pregnancy details

What You'll Get

📋 How It Works

How Pregnancy Due Dates Are Calculated

Worked Example

Pregnancy Calculator — Frequently Asked Questions

How is a pregnancy due date calculated?

How accurate is a pregnancy due date?

When do the trimesters start and end?

What prenatal appointments should I schedule?

What are the earliest signs of pregnancy?

What is gestational age vs fetal age?

When can I find out the sex of the baby?

What foods should be avoided during pregnancy?

→ You might also need