🌱 Health Promotion · Lesson 5 of 6 · 7 min
Prenatal Basics: Due Dates, Visits and Danger Signs
🤰 A woman's last period started on May 10. She wants to know her due date. The exam wants you to do it in your head, then tell her which three symptoms mean 'call now'.
💡 Key idea
LMP minus 3 months plus 7 days. Visits q4 weeks to 28, q2 to 36, then weekly. Bleeding, fluid, severe headache or visual changes, and reduced fetal movement are call-now signs.
🧠 Why it matters
NAEGELE'S RULE: first day of the last menstrual period, subtract 3 months, add 7 days, and add a year when needed. May 10 becomes February 17 of the next year. Pregnancy is confirmed by POSITIVE signs: fetal heart tones by Doppler at about 10 to 12 weeks, ultrasound visualization, or fetal movement felt by the examiner. Presumptive signs (missed period, nausea, breast changes, quickening at 16 to 20 weeks) and probable signs (positive hCG, Hegar's, Goodell's and Chadwick's signs) are not proof. Visits are every 4 weeks until 28 weeks, every 2 weeks until 36, then weekly. Take 400 mcg of FOLIC ACID before conception and 600 mcg daily during pregnancy to prevent neural tube defects. Avoid alcohol, raw or undercooked meat and fish, unpasteurized dairy and deli meats (listeria), high-mercury fish, and cat litter (toxoplasmosis). DANGER SIGNS to report immediately: vaginal bleeding, a gush of fluid, severe headache, blurred vision or epigastric pain (preeclampsia), fever, painful urination, persistent vomiting, and decreased fetal movement.
🏥 In the real world
🌸 At 32 weeks a client mentions a 'bad headache that won't quit' and spots in her vision, then adds that her rings are tight. The nurse checks her blood pressure (156/98), tests her urine for protein, and calls the provider. Those three complaints are the textbook picture of preeclampsia, and the exam expects you to connect them before the seizure does.
📌 Takeaways
- Naegele's rule: LMP − 3 months + 7 days (+ 1 year)
- Folic acid 400 mcg before conception, 600 mcg during pregnancy
- Headache, visual changes and epigastric pain in late pregnancy mean preeclampsia until proven otherwise
📖 Terms in this lesson
Naegele's rule: Estimated due date: first day of the last period, minus three months, plus seven days, plus a year.
TORCH (infections that cross the placenta): Toxoplasmosis, Other (syphilis, varicella, parvovirus, HIV), Rubella, Cytomegalovirus, Herpes simplex: infections that can pass to the fetus or newborn, in pregnancy or at birth, and cause birth defects.
GTPAL (obstetric history): Gravida (total pregnancies), Term births (37 weeks or more), Preterm births (20 to 36 weeks), Abortions (losses before 20 weeks), Living children: how to record an obstetric history.
Hemoglobin in pregnancy: Anemia in pregnancy is a hemoglobin under 11 g/dL in the first and third trimesters and under 10.5 g/dL in the second, because plasma volume expands faster than red cells; iron with vitamin C is the usual fix.
Gestational diabetes screen (1-hour glucose challenge): At 24 to 28 weeks the client drinks 50 grams of glucose and a 1-hour value of 130 to 140 mg/dL or higher (the cutoff varies by practice) is a positive screen that sends her to the 3-hour test.
3-hour glucose tolerance test (gestational diabetes): After a 100-gram glucose load the cutoffs are fasting 95, 1-hour 180, 2-hour 155 and 3-hour 140 mg/dL (Carpenter-Coustan), and two or more values at or above them diagnose gestational diabetes.
✅ Test yourself
A client's last menstrual period began on October 20. Using Naegele's rule, what is the estimated due date?
- July 27
- July 13
- August 13
- June 27
Answer: A · July 27
October 20 minus 3 months is July 20; plus 7 days is July 27 of the following year.
Which finding is a POSITIVE sign of pregnancy?
- A positive home urine pregnancy test
- Fetal heart tones heard by Doppler
- Morning nausea, vomiting and fatigue
- Breast tenderness and darkened areolae
Answer: B · Fetal heart tones heard by Doppler
Positive signs come from the fetus itself: heart tones, ultrasound visualization or examiner-felt movement. Hormone tests are only probable.
A client at 30 weeks calls the clinic. Which complaint requires immediate evaluation?
- Occasional heartburn after meals
- Increased urination
- Severe headache with blurred vision
- Mild ankle swelling at the end of the day
Answer: C · Severe headache with blurred vision
Severe headache and visual disturbances are warning signs of preeclampsia. The other three are common discomforts of pregnancy.
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