01
Signs of Pregnancy
Three categories — only positive signs CONFIRM pregnancy.
- Presumptivesubjective
- Reported by the mother. Could have other causes: amenorrhea, nausea/vomiting, breast tenderness, fatigue, urinary frequency, quickening (first fetal movement felt by mom).
- Probableobjective
- Found by the examiner. Strongly suggest pregnancy but could have other causes: positive hCG (pregnancy test), Hegar sign (soft lower uterine segment), Chadwick sign (bluish cervix/vagina), Goodell sign (softened cervix), uterine enlargement, ballottement.
- Positivedefinitive
- Can ONLY mean pregnancy. No other explanation: fetal heartbeat by Doppler/ultrasound, visualization of fetus on ultrasound, fetal movement felt by examiner.
Exam Tip
A positive pregnancy test (hCG) is a PROBABLE sign, not a positive sign — hCG can be elevated in molar pregnancy or certain tumors. Only fetal heartbeat, ultrasound visualization, and examiner-felt fetal movement are positive (confirmatory) signs. This distinction is heavily tested.
Don't want to read it all?
Every key point in this guide fits on one free printable page. Jump to the free cheatsheet PDF →
02
GTPAL (Obstetric History)
Know how to calculate GTPAL — it appears on every OB exam.
- GGravida
- Total number of pregnancies (including current).
- TTerm
- Number of births at ≥37 weeks.
- PPreterm
- Number of births between 20–36 weeks.
- AAbortions
- Pregnancy losses before 20 weeks (includes elective abortions and miscarriages).
- LLiving
- Number of living children currently.
Worked Example
A woman is currently pregnant. She previously had one full-term vaginal delivery (living child), one premature delivery at 32 weeks (living child), and one miscarriage at 10 weeks.
- G4 — 4 pregnancies total (3 previous + current)
- T1 — 1 term birth
- P1 — 1 preterm birth
- A1 — 1 abortion (miscarriage)
- L2 — 2 living children
- Answer: G4 T1 P1 A1 L2
Key Distinctions
Gravida counts PREGNANCIES, not babies. Twins = 1 pregnancy = G1. Para counts DELIVERIES after 20 weeks, not babies. Twins delivered at term = T1 (one delivery). Abortions include ALL losses before 20 weeks — both elective and spontaneous (miscarriage).
03
Nagele's Rule (Estimated Due Date)
Calculate the EDD from the first day of the LMP.
The Formula
- Months 4–12: Subtract 3 months, add 7 days, add 1 year
- Months 1–3: Add 9 months, add 7 days, same year
Examples
- LMP: November 15, 2025 → November – 3 = August, 15 + 7 = 22, + 1 year → August 22, 2026
- LMP: February 5, 2025 → February + 9 = November, 5 + 7 = 12 → November 12, 2025
Other Key Dates
- Normal pregnancy: 40 weeks (280 days) from LMP
- Trimesters: 1st (weeks 1–12), 2nd (weeks 13–27), 3rd (weeks 28–40)
- Viability: ~24 weeks (earliest a fetus can survive outside the womb)
? LMP is October 10 — what is the EDD using Nagele's rule?
October – 3 = July, 10 + 7 = 17, + 1 year → July 17 of the following year.
04
Fetal Development Milestones
Know the key milestones by week — these are commonly tested.
- 4 weeks
- Heart begins to beat. Neural tube forming.
- 8 weeks
- All major organs formed (organogenesis complete). Most vulnerable to teratogens.
- 10 weeks
- Fetal period begins (no longer embryo). External genitalia begin to differentiate.
- 12 weeks
- Gender distinguishable by ultrasound. Kidneys produce urine. Heartbeat detectable by Doppler.
- 16 weeks
- Quickening may begin (mom feels first movement — multigravidas feel earlier). Lanugo and meconium forming.
- 20 weeks
- Vernix caseosa covers skin. Fetal heartbeat audible with fetoscope. Eyebrows and hair present. Halfway point.
- 24 weeks
- Age of viability. Lungs begin producing surfactant (but not enough yet). Eyes open.
- 28 weeks
- Surfactant production increases. Eyes can open and close. Fat deposits begin.
- 32 weeks
- Subcutaneous fat increases. Bones fully developed but soft. Fingernails reach fingertips.
- 36 weeks
- Lungs approaching maturity. L/S ratio reaching 2:1. Lanugo disappearing.
- 38–40 weeks
- Full term. Lungs mature. Firm cartilage in ears. Creases on entire sole of foot.
Weeks 3–8 = Highest Teratogen Risk
Organogenesis (organ formation) occurs during weeks 3–8. This is when the embryo is MOST vulnerable to teratogens (drugs, alcohol, infections, radiation). After 8 weeks, the major organs are formed and the risk of structural defects decreases — but the brain continues developing throughout pregnancy.
05
Prenatal Visit Schedule
Frequency increases as pregnancy progresses.
- Weeks 1–28
- Every 4 weeks.
- Weeks 28–36
- Every 2 weeks.
- Weeks 36–40
- Every week.
Every Visit Includes
- Weight, blood pressure, urine (protein and glucose)
- Fundal height measurement (after 20 weeks: fundal height in cm ≈ gestational age in weeks)
- Fetal heart rate (normal: 110–160 bpm)
- Assessment for edema, fetal movement
- Review of danger signs and questions
Fundal Height Rule
After 20 weeks, fundal height in centimeters approximately equals gestational age in weeks (±2 cm). If the measurement is significantly larger → think multiple gestation, polyhydramnios, or wrong dates. Significantly smaller → think IUGR, oligohydramnios, or wrong dates.
06
Prenatal Labs & Screening
Know what's drawn, when, and what the results mean.
First Visit Labs
- CBC — check for anemia (Hgb <11 g/dL in pregnancy = anemia)
- Blood type, Rh factor, antibody screen — identify Rh-negative mothers for RhoGAM
- Rubella titer — check immunity (if non-immune, vaccinate postpartum — MMR is live, contraindicated during pregnancy)
- Hepatitis B surface antigen (HBsAg)
- HIV screening
- Syphilis (RPR/VDRL)
- Urine culture — screen for asymptomatic bacteriuria (treat to prevent pyelonephritis)
- Pap smear (if not recent)
- Chlamydia/Gonorrhea
Later Screening
- First trimester screen10–14 weeks
- Screens for trisomy 13, 18, 21 (Down syndrome). Nuchal translucency + blood markers.
- NIPT (cell-free DNA)≥10 weeks
- Non-invasive blood test for chromosomal abnormalities. High accuracy.
- Quad screen / AFP15–20 weeks
- Screens for neural tube defects (elevated AFP) and Down syndrome (low AFP).
- CVS10–12 weeks
- Invasive — definitive diagnosis. Samples placental tissue. Risk of miscarriage.
- Amniocentesis≥14 weeks
- Invasive — definitive. Samples amniotic fluid. Also checks L/S ratio for lung maturity (≥2:1 = mature).
- GBS culture35–37 weeks
- Group B Strep vaginal/rectal culture. If positive → IV antibiotics during labor (penicillin).
- 1-hour glucose challenge24–28 weeks
- Screens for gestational diabetes. If ≥140 mg/dL → 3-hour GTT to confirm.
AFP Levels
Elevated AFP → think open neural tube defect (spina bifida, anencephaly) or abdominal wall defect. Low AFP → think Down syndrome (trisomy 21). AFP is part of the quad screen at 15–20 weeks. Abnormal results require follow-up (ultrasound, amniocentesis) — it's a screening test, not diagnostic.
07
Prenatal Nutrition
Eating for two doesn't mean double portions — it means smart nutrition.
- Caloric increase: Only ~300 extra calories/day in 2nd and 3rd trimesters
- Weight gain: Normal BMI → 25–35 lbs total. Underweight → 28–40 lbs. Overweight → 15–25 lbs. Obese → 11–20 lbs.
- Folic acid: 400–800 mcg daily — ideally starting BEFORE conception. Prevents neural tube defects.
- Iron: 27 mg/day. Take with vitamin C for absorption. Avoid with dairy/antacids.
- Calcium: 1,000 mg/day. Important for fetal bone development.
- DHA: 200–300 mg/day for fetal brain/eye development.
- Protein: 60–70 g/day (increased from non-pregnant 46 g/day).
Foods to AVOID
- Raw/undercooked meat, eggs, sushi — risk of Toxoplasma, Salmonella, Listeria
- High-mercury fish: shark, swordfish, king mackerel, tilefish
- Unpasteurized dairy and juice — Listeria risk
- Deli meats and hot dogs unless heated until steaming (Listeria)
- Alcohol — no safe amount. Causes fetal alcohol spectrum disorder (FASD).
- Caffeine — limit to <200 mg/day (about one 12-oz cup of coffee)
- Cat litter — Toxoplasmosis risk (have someone else change it)
08
Common Pregnancy Discomforts & Interventions
Know the teaching for each — these are practical exam questions.
- Nausea/Vomiting1st trimester
- Eat small frequent meals, dry crackers before rising, avoid greasy/spicy food, ginger tea. Usually resolves by 12–14 weeks. Hyperemesis gravidarum = severe, needs medical treatment.
- Urinary frequency1st & 3rd
- Normal from uterine pressure on bladder. Kegel exercises. Don't reduce fluids. Report pain/burning (UTI).
- Fatigue1st & 3rd
- Rest when possible, prioritize sleep, light exercise, good nutrition.
- Heartburn/GERD2nd & 3rd
- Small frequent meals, avoid lying down after eating, elevate HOB, antacids (Tums — also provides calcium). Avoid sodium bicarbonate.
- Constipationall trimesters
- Increase fiber and fluids, exercise, stool softeners if needed. Iron supplements worsen it.
- Backache2nd & 3rd
- Good body mechanics, pelvic tilt exercises, flat shoes, firm mattress, proper posture.
- Leg cramps3rd trimester
- Dorsiflex the foot (pull toes toward shin). Calcium/magnesium supplements. Stretch before bed.
- Edema (mild)3rd trimester
- Elevate feet, avoid prolonged standing, lie on left side, avoid tight clothing. Report sudden facial/hand swelling (preeclampsia!).
- Varicose veins2nd & 3rd
- Avoid crossing legs, elevate legs, support stockings, avoid prolonged standing.
- Round ligament pain2nd trimester
- Sharp/pulling pain in lower abdomen with position changes. Normal — supportive measures. Slow position changes.
09
Danger Signs of Pregnancy
These require IMMEDIATE provider notification — teach patients to report any of these.
- Vaginal bleeding at any time during pregnancy
- Severe headache that does not resolve (preeclampsia)
- Visual disturbances — blurred vision, seeing spots or flashes (preeclampsia)
- Epigastric or RUQ pain (HELLP syndrome, liver involvement)
- Sudden swelling of face or hands (preeclampsia — distinguishable from normal ankle edema)
- Decreased or absent fetal movement — "kick counts" <10 movements in 2 hours
- Gush of fluid from vagina (rupture of membranes — risk of infection and cord prolapse)
- Fever >100.4°F (infection)
- Persistent vomiting (hyperemesis gravidarum — dehydration, electrolyte imbalance)
- Dysuria with fever (UTI → risk of pyelonephritis → preterm labor)
- Regular contractions before 37 weeks (preterm labor)
Preeclampsia Warning Triad
If a question describes a pregnant patient with: severe headache + visual changes + facial/hand swelling → think preeclampsia. Check blood pressure (≥140/90 = hypertensive), check urine for protein, and notify the provider immediately. Preeclampsia can progress to eclampsia (seizures) and HELLP syndrome.
10
Fetal Testing
Know what each test measures and what the results mean.
- Kick Counts
- Mother counts fetal movements. ≥10 movements in 2 hours = reassuring. <10 → contact provider. Best done after meals, side-lying.
- NSTNon-Stress Test
- Monitors FHR in response to fetal movement. Reactive (normal): 2 or more accelerations of ≥15 bpm lasting ≥15 seconds in 20 minutes. Non-reactive: criteria not met → may need further testing (BPP, CST).
- BPPBiophysical Profile
- 5-component assessment: FHR reactivity (NST) + fetal breathing + fetal movement + fetal tone + amniotic fluid volume. Score 0–10 (2 points each). 8–10 = normal. 6 = equivocal (retest). ≤4 = abnormal (delivery may be indicated).
- CSTContraction Stress Test
- Monitors FHR response to contractions (induced with oxytocin or nipple stimulation). Negative (normal): no late decelerations. Positive (abnormal): late decelerations with contractions = uteroplacental insufficiency.
- Amniocentesis
- Samples amniotic fluid. L/S ratio ≥2:1 = fetal lung maturity. Presence of phosphatidylglycerol (PG) = mature. Post-procedure: monitor for leaking, contractions, FHR changes.
- Ultrasound
- Confirms pregnancy, gestational age, fetal anomalies, placental location, amniotic fluid volume (AFI), gender. Non-invasive, no radiation.
NST — Reactive vs Non-Reactive
Remember: Reactive = Reassuring (both start with "R"). A reactive NST means the baby's heart rate accelerates appropriately with movement — the baby is healthy. A non-reactive NST means further evaluation is needed — it doesn't automatically mean something is wrong, just that more information is needed.
? A BPP score of 6 — what does the nurse do next?
A score of 6 is equivocal — it means repeat testing is indicated (retest within 24 hours or pursue additional evaluation). It is not automatically alarming but requires follow-up. A score of ≤4 is abnormal and delivery may be indicated.
11
Frequently Asked Questions
Common student questions on this topic.
What is Nägele's rule for calculating the estimated due date?
Take the first day of the last menstrual period (LMP), subtract 3 months, then add 7 days and 1 year. Example: LMP = July 10, 2026 → April 17, 2027 EDD. Nägele's rule assumes a 28-day cycle with ovulation on day 14. Ultrasound dating in the first trimester is more accurate but Nägele's is still the standard for charting and clinical use.
What are the presumptive, probable, and positive signs of pregnancy?
Presumptive (subjective, could be other causes): amenorrhea, nausea/vomiting, breast tenderness, fatigue, urinary frequency, quickening. Probable (objective examiner findings, still not conclusive): Goodell's sign, Chadwick's sign, Hegar's sign, positive pregnancy test, Braxton Hicks. Positive (only pregnancy could cause): fetal heartbeat heard, fetal movement felt by examiner, ultrasound visualization. Only positive signs definitively confirm pregnancy.
What prenatal vitamins and supplements are recommended?
Folic acid 400–800 mcg/day before conception and through the first trimester — prevents neural tube defects (spina bifida). Iron 27 mg/day to prevent anemia. Calcium 1,000 mg/day. Most prenatal vitamins cover all these. Counsel to avoid vitamin A in large doses (teratogenic) and limit caffeine to under 200 mg/day. No alcohol or smoking. Avoid raw fish, deli meats, and unpasteurized cheeses (listeria).
What are the danger signs in pregnancy that require immediate provider notification?
Teach the patient to call the provider for: vaginal bleeding, severe abdominal pain, severe persistent headache, blurred vision or spots, swelling of the face or hands, sudden weight gain, decreased fetal movement, leaking fluid from the vagina, painful or burning urination, persistent vomiting, fever, or signs of preterm labor (regular contractions before 37 weeks). These can signal preeclampsia, placental problems, infection, or preterm labor.
What labs are checked during pregnancy?
Initial visit: blood type, Rh, antibody screen, CBC, urinalysis, urine culture, rubella titer, HIV, hepatitis B, syphilis (RPR), gonorrhea/chlamydia, Pap smear. At 24–28 weeks: glucose tolerance test (1-hour screen → 3-hour if positive) for gestational diabetes, and another antibody screen for Rh-negative women. At 35–37 weeks: Group B strep (GBS) swab — if positive, antibiotics during labor.
What is Rh incompatibility and how is it prevented?
Rh incompatibility occurs when an Rh-negative mother carries an Rh-positive fetus. If fetal Rh+ blood mixes with maternal Rh− blood, the mother forms antibodies. The first pregnancy is usually fine, but in subsequent pregnancies the antibodies can attack Rh+ fetal blood. Prevention: give RhoGAM (Rh immunoglobulin) at 28 weeks, within 72 hours of delivery if baby is Rh+, and after any bleeding event (miscarriage, amniocentesis, trauma).
12
Quick-Reference Cheatsheet
Every key point from this guide on a single printable page.
Antepartum (Prenatal) Care Cheatsheet
Free, printable PDF · no spam · returning visitors skip the email step.