CNM cheat sheet

Naegele's rule: EDD = first day of LMP + 7 days − 3 months + 1 year; redate if first-trimester ultrasound differs by more than 7 days.

Gravida counts all pregnancies including the current one; para counts births at ≥20 weeks gestation regardless of outcome (e.g., G3P2).

Fetal heart tones are detectable by handheld Doppler at 10–12 weeks and by fetoscope at 18–20 weeks.

Cell-free DNA screening may be offered from 10 weeks; maternal serum AFP is drawn at 15–20 weeks; anatomy survey at 18–22 weeks.

Gestational diabetes screening: 50-g one-hour glucose challenge at 24–28 weeks; threshold 130–140 mg/dL triggers a 100-g, 3-hour diagnostic test.

Fundal height in centimeters approximates gestational age from 20 to 36 weeks, within ±2–3 cm.

Anti-D immune globulin 300 mcg is given at 28 weeks to unsensitized Rh-negative women and within 72 hours after birth of an Rh-positive infant.

Blood pressure ≥140/90 mm Hg on two occasions ≥4 hours apart after 20 weeks defines gestational hypertension; adding proteinuria or organ dysfunction defines preeclampsia.

Group B streptococcus culture is collected at 36 0/7–37 6/7 weeks; intravenous penicillin is the preferred intrapartum prophylaxis.

First stage: latent phase 0–6 cm with slow change; active phase begins at 6 cm and ends at full dilation.

Minimum normal active-phase cervical change is approximately 0.5–1 cm per hour; arrest is no change ≥6 cm with ruptured membranes and adequate contractions.

Second-stage duration limits: nullipara up to 3 hours (4 with epidural); multipara up to 2 hours (3 with epidural).

Normal fetal heart rate baseline is 110–160 bpm; bradycardia is <110 for ≥10 minutes, tachycardia >160 for ≥10 minutes.

Early decelerations reflect head compression and are benign; variable decelerations reflect cord compression; late decelerations reflect uteroplacental insufficiency.

Category III tracing: absent variability with recurrent late or variable decelerations, bradycardia, or a sinusoidal pattern - requires prompt evaluation and possible expedited delivery.

Bishop score ≥6 indicates a favorable cervix for induction; lower scores predict longer induction and higher failure risk.

Tachysystole is more than 5 contractions in 10 minutes averaged over 30 minutes; reduce or stop oxytocin and reposition.

Shoulder dystocia sequence: McRoberts maneuver plus suprapubic pressure, then rotational maneuvers (Rubin II, Woods screw), then delivery of the posterior arm.

Immediately postpartum the fundus is firm, midline, at the umbilicus; it descends roughly 1 cm per day and should be palpable abdominally for about 2 weeks.

Lochia rubra lasts 1–3 days, serosa 4–10 days, and alba beyond 10 days; foul odor or return to rubra suggests infection or retained products.

Postpartum hemorrhage: cumulative blood loss ≥1000 mL or bleeding with signs of hypovolemia within 24 hours of birth, by any route.

Uterine atony is the most common cause of postpartum hemorrhage; treat with massage, oxytocin, then methylergonovine (avoid in hypertension) or carboprost (avoid in asthma).

Postpartum endometritis presents with fever ≥38°C on two of the first 10 days plus uterine tenderness; treat with clindamycin plus gentamicin.

Mastitis is most often caused by Staphylococcus aureus; management includes continued breastfeeding, analgesics, and dicloxacillin or cephalexin when antibiotics are indicated.

Edinburgh Postnatal Depression Scale score ≥10 or any positive answer to the self-harm item warrants further evaluation.

Exclusive breastfeeding averages 8–12 feedings per 24 hours; colostrum is produced for the first 2–3 days before transitional milk.

ACOG recommends contact with the obstetric care team within 3 weeks postpartum and a comprehensive visit no later than 12 weeks.

Apgar score at 1 and 5 minutes assigns 0–2 points each for heart rate, respiratory effort, muscle tone, reflex irritability, and color.

Term newborns may lose up to 7–10% of birth weight in the first week and regain birth weight by 10–14 days.

All newborns receive 0.5–1 mg vitamin K1 intramuscularly and erythromycin 0.5% ophthalmic ointment after birth.

Heel-stick newborn screening is collected between 24 and 72 hours of age, after feeding has begun.

Jaundice appearing within the first 24 hours is pathologic; physiologic jaundice peaks at days 3–5 and is treated with phototherapy per hour-specific nomograms.

Normal newborn vital signs: heart rate 110–160 bpm, respiratory rate 40–60 breaths/min, axillary temperature 36.5–37.5°C.

Umbilical arterial pH <7.0 with base deficit ≥12 mmol/L indicates significant metabolic acidemia at birth.

Hypoglycemia is generally defined as glucose <45 mg/dL in the first 24 hours; screen infants of diabetic mothers and those large or small for gestational age.

Blood pressure categories: normal <120/80; elevated 120–129/<80; stage 1 130–139/80–89; stage 2 ≥140/90 mm Hg.

Cervical cancer screening: cytology alone every 3 years from 21–29; at 30–65, cytology every 3 years, co-testing every 5 years, or primary HPV testing every 5 years.

USPSTF recommends biennial mammography for women aged 40–74.

Colorectal cancer screening is recommended for average-risk adults aged 45–75.

Diabetes diagnosis: A1c ≥6.5%, fasting glucose ≥126 mg/dL, 2-hour OGTT ≥200 mg/dL, or random glucose ≥200 mg/dL with symptoms.

DEXA screening for osteoporosis is recommended for all women aged 65 and older and for younger postmenopausal women with elevated risk.

One dose of Tdap is recommended during each pregnancy at 27–36 weeks gestation, regardless of the prior dose interval.

Statin therapy is recommended for adults aged 40–75 with at least one cardiovascular risk factor and a 10-year ASCVD risk ≥10%.

Most effective reversible methods: implant and levonorgestrel IUDs (<1% typical-use failure); combined oral contraceptives have about 7–9% typical-use failure.

Absolute contraindications to combined hormonal contraceptives include migraine with aura, smoking at age ≥35, prior VTE, uncontrolled hypertension, and known thrombophilia.

Emergency contraception: levonorgestrel up to 72 hours, ulipristal acetate up to 120 hours, and copper IUD placement within 5 days (most effective).

Menopause is defined as 12 months of amenorrhea without another cause; FSH typically exceeds 30 mIU/mL.

PCOS Rotterdam criteria require two of three: oligo/anovulation, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology on ultrasound.

Bacterial vaginosis: Amsel criteria (three of four - homogeneous discharge, pH >4.5, positive whiff test, clue cells); first-line treatment is metronidazole.

Endometriosis classically causes dysmenorrhea, dyspareunia, and infertility; laparoscopy is the diagnostic standard and first-line treatment is hormonal suppression or NSAIDs.

ASC-US cytology with negative HPV may repeat co-testing in 3 years; ASC-US with positive HPV warrants colposcopy.

Informed consent requires patient capacity, disclosure of risks/benefits/alternatives, comprehension, and voluntariness, documented in the record.

HIPAA permits disclosure for treatment, payment, and operations, and requires minimum necessary use; breaches of unsecured PHI require notification.

CNM scope of practice is defined by ACNM: primary care, gynecologic and reproductive care, and care during pregnancy, birth, and the postpartum period.

State law determines whether CNMs have full, reduced, or restricted prescriptive authority and whether physician collaboration is required.

Mandatory reporting obligations include suspected child or elder abuse and specified communicable diseases, per state statute.

EMTALA requires Medicare-participating hospitals to provide a medical screening examination and stabilizing treatment regardless of insurance status.

The Belmont Report principles guiding human-subjects research are respect for persons, beneficence, and justice.

Sentinel events (e.g., wrong-site surgery, retained foreign body, maternal death from a preventable cause) require root-cause analysis and disclosure.