Pregnancy and Birth Risk Factors · 9 min read
Antepartum Risk Factors and Complications
Diabetes in Pregnancy
- Pregestational diabetes (type 1 or 2): preconception HbA1c target below 6.5% when achievable without hypoglycemia. Poor periconception control causes congenital anomalies (cardiac, neural tube, caudal regression) and miscarriage.
- GDM screening at 24–28 weeks, earlier for patients with risk factors (obesity, prior GDM, prior macrosomic infant, strong family history).
- Pregnancy glucose targets: fasting below 95 mg/dL, 1-hour postprandial below 140, 2-hour below 120. Insulin is preferred when nutrition therapy fails; metformin and glyburide cross the placenta.
- Intrapartum glucose is kept about 70–110 mg/dL, because maternal hyperglycemia in labor causes fetal hyperinsulinemia and neonatal hypoglycemia.
| Method | Test | Diagnosis |
|---|---|---|
| Two-step | 50-g, 1-hour glucose challenge (nonfasting); positive at 130–140 mg/dL or higher, then a fasting 100-g, 3-hour OGTT | Two or more values at or above 95 (fasting), 180 (1 h), 155 (2 h), 140 (3 h) mg/dL |
| One-step | Fasting 75-g, 2-hour OGTT | One value at or above 92 (fasting), 180 (1 h), 153 (2 h) mg/dL |
Postpartum implications: GDM insulin and oral agents are usually stopped after birth; type 1 diabetes needs a sharp insulin reduction (risk of maternal hypoglycemia, especially with breastfeeding). After GDM, a 75-g, 2-hour OGTT at 4–12 weeks postpartum, then screening every 1–3 years for life (high lifetime risk of type 2 diabetes). Newborn: macrosomia and shoulder dystocia, hypoglycemia, RDS, polycythemia, hyperbilirubinemia, hypocalcemia (Chapter 26).
Hypertensive Disorders
| Disorder | Definition | Maternal and newborn implications |
|---|---|---|
| Chronic hypertension | BP 140/90 mm Hg or higher before pregnancy or before 20 weeks | Superimposed preeclampsia risk; FGR; continue labetalol or nifedipine postpartum |
| Gestational hypertension | New BP 140/90 or higher after 20 weeks on two readings at least 4 hours apart, without proteinuria or end-organ signs | May progress to preeclampsia; same postpartum BP follow-up |
| Preeclampsia | New hypertension after 20 weeks plus proteinuria (300 mg/24 h or more, protein/creatinine ratio 0.3 or higher) or new end-organ dysfunction | Placental insufficiency: FGR, oligohydramnios, preterm birth; can first appear or worsen up to 6 weeks postpartum |
| Preeclampsia with severe features | SBP 160 or higher or DBP 110 or higher; platelets below 100,000/µL; transaminases twice normal or RUQ/epigastric pain; creatinine above 1.1 mg/dL or doubled; pulmonary edema; new headache or visual changes | Treat severe-range BP within 30–60 minutes (labetalol, hydralazine, immediate-release nifedipine); magnesium sulfate |
| HELLP syndrome | Hemolysis, elevated liver enzymes, low platelets; may occur without severe hypertension | Epigastric/RUQ pain, nausea, malaise; DIC, hepatic hematoma; newborn often preterm and growth restricted |
| Eclampsia | New-onset seizures with a hypertensive disorder, no other cause | Protect airway, side-lying, magnesium; check fetal status; can occur postpartum |
- Low-dose aspirin (81 mg) from 12–28 weeks (ideally before 16) until birth reduces preeclampsia in high-risk patients.
- Magnesium sulfate (commonly 4–6 g IV load, then 1–2 g/h) continues about 24 hours after birth; therapeutic level about 4.8–8.4 mg/dL. Monitor reflexes, respirations, urine output, and level; calcium gluconate is the antidote. Magnesium increases uterine atony and PPH risk.
- Newborn after maternal magnesium: hypotonia, weak suck, respiratory depression, and lethargy; after maternal labetalol: monitor for hypoglycemia and bradycardia.
Infections
| Organism | Perinatal risk | Maternal and newborn nursing implications |
|---|---|---|
| Group B streptococcus (GBS) | Rectovaginal colonization; screened at 36 0/7–37 6/7 weeks; leading cause of early-onset sepsis | Adequate IAP = penicillin, ampicillin, or cefazolin given 4 hours or more before birth. Inadequate IAP or other risk factors: newborn observation and EOS risk assessment |
| Herpes simplex virus | Highest risk with primary infection near birth; neonatal HSV (skin, CNS, disseminated) | Cesarean for active lesions or prodrome in labor; suppressive acyclovir from 36 weeks. Hand hygiene, cover lesions; breastfeed unless lesion on breast |
| Cytomegalovirus | Most common congenital viral infection; leading nongenetic cause of hearing loss | Infant who fails the hearing screen: CMV testing within the first 21 days. Hand hygiene with toddler saliva and diapers |
| Hepatitis B | Perinatal transmission, chronic infection | Infant of HBsAg-positive mother: hepatitis B vaccine and HBIG within 12 hours; breastfeeding is encouraged |
| Hepatitis C | Vertical transmission about 5–6% | Breastfeed unless nipples are cracked or bleeding; infant HCV testing per pediatric protocol |
| HIV | Transmission below 1% with ART and viral suppression | IV zidovudine in labor if viral load above 1,000 copies/mL or unknown; infant ARV prophylaxis started as soon as possible, ideally within 6 hours; feeding by shared decision-making when mother has sustained viral suppression on ART |
| Syphilis | Congenital syphilis (rash on palms and soles, snuffles, hepatosplenomegaly, stillbirth) | Screen at first visit, again at 28 weeks and at birth when at risk; penicillin G is the only treatment; no infant discharged without known maternal serologic status |
| Chlamydia / gonorrhea | Preterm birth; neonatal conjunctivitis (gonococcal 2–5 days, chlamydial 5–14 days) and chlamydial pneumonia | Erythromycin eye prophylaxis prevents gonococcal (not reliably chlamydial) ophthalmia; treat partners |
| Rubella | First-trimester infection: cataracts, deafness, heart defects | Nonimmune mother: MMR postpartum (safe with breastfeeding); avoid pregnancy 4 weeks |
| Varicella | Congenital varicella syndrome; severe maternal pneumonia | Exposed nonimmune mother: VariZIG within 10 days. Maternal onset 5 days before to 2 days after birth: infant receives VariZIG; airborne and contact isolation |
| Toxoplasmosis | Chorioretinitis, hydrocephalus, intracranial calcifications | Avoid undercooked meat and cat litter |
| Triple I (chorioamnionitis) | Intrauterine infection, usually ascending after rupture of membranes | Mother: endometritis, atony, PPH. Newborn: early-onset sepsis evaluation |
Anemia and Cardiac Disease
- Iron deficiency anemia is the most common anemia of pregnancy; treat with oral iron (with vitamin C, apart from calcium and dairy) or IV iron. It increases fatigue, transfusion need after PPH, and possibly postpartum depression; infants may have lower iron stores.
- Sickle cell disease: risk of crises, infection, VTE, preeclampsia, and FGR. Thalassemia trait: mild microcytic anemia that does not respond to iron; avoid unnecessary iron.
- Cardiac disease: decompensation is most likely when plasma volume peaks (late 2nd trimester), during labor, and in the first 24–72 hours postpartum, when autotransfusion and mobilization of extravascular fluid raise preload. Watch for dyspnea, orthopnea, crackles, tachycardia, and SpO₂ below 95%; strict intake and output; avoid fluid boluses; upright positioning.
- Peripartum cardiomyopathy and postpartum management are covered in Chapter 18. A parent with congenital heart disease raises the newborn's risk of CHD; review fetal echocardiogram results.
Substance Use
| Substance | Pregnancy risks | Newborn and postpartum implications |
|---|---|---|
| Tobacco / nicotine | FGR, previa, abruption, PPROM, preterm birth | Higher SIDS risk; smoke-free home and car; nicotine replacement is preferred over continued smoking |
| Opioids (prescribed or illicit) | Overdose, infection, FGR, preterm birth; medically supervised withdrawal is not recommended | MOUD (buprenorphine or methadone) is the standard of care. NOWS (Chapter 23). Breastfeeding supported on stable MOUD without illicit use. Postpartum overdose risk is highest in the first year |
| Alcohol | No safe amount or time | FASD: smooth philtrum, thin upper lip, short palpebral fissures, growth and CNS deficits |
| Cannabis | Possible FGR and neurodevelopmental effects; no safe level established | THC passes into breast milk; advise abstinence while breastfeeding |
| Cocaine / methamphetamine | Hypertension, abruption, FGR, preterm birth | Irritability, poor feeding; active use is a contraindication to breastfeeding |
| Over-the-counter drugs | NSAIDs after about 20 weeks: fetal renal dysfunction and oligohydramnios; in the 3rd trimester, ductus arteriosus constriction | Acetaminophen is the preferred analgesic in pregnancy; NSAIDs are appropriate postpartum for most patients |
Screen all patients with a validated verbal tool; toxicology testing follows policy and informed consent. Federal law (CAPTA) requires a plan of safe care for infants affected by prenatal substance exposure; notification is not the same as a report of abuse. Use person-first, nonjudgmental language.
Preterm Labor and Post-term Pregnancy
- Preterm birth: before 37 0/7 weeks; late preterm is 34 0/7–36 6/7 weeks. Risk factors: prior spontaneous preterm birth, short cervix, multiples, infection, smoking, and short interpregnancy interval.
- Prevention: vaginal progesterone for a short cervix in the midtrimester; cerclage for selected patients. 17-OHP caproate (Makena) has been withdrawn from the market and is no longer used.
- Antenatal corticosteroids (betamethasone 12 mg IM, 2 doses 24 hours apart) from 24 0/7 to 33 6/7 weeks (and in selected late preterm patients) reduce RDS, IVH, and mortality. Late preterm exposure increases neonatal hypoglycemia.
- Magnesium sulfate for fetal neuroprotection before 32 weeks reduces cerebral palsy.
- Tocolytics delay birth up to 48 hours for steroids and transfer: nifedipine, indomethacin (before 32 weeks, short course), and terbutaline (short-term only).
- Late-term is 41 0/7–41 6/7 weeks; post-term is 42 0/7 weeks or later. Placental aging causes oligohydramnios, meconium, and macrosomia. Post-term newborn: dry peeling skin, long nails, little vernix, hypoglycemia, polycythemia, and meconium aspiration.
Multiple Gestation, Growth, and Amniotic Fluid
| Condition | Key facts | Postpartum and newborn implications |
|---|---|---|
| Multiple gestation | Monochorionic twins share a placenta: twin-twin transfusion syndrome, selective FGR. Typical birth timing: dichorionic 38 weeks; monochorionic-diamniotic 34–37 weeks | Mother: PPH (overdistention), preeclampsia, anemia. Newborns: prematurity, discordant growth, TTTS donor (anemia) vs recipient (polycythemia) |
| Fetal growth restriction | EFW below the 10th percentile. Symmetric = early insult (genetic, infection); asymmetric (head-sparing) = later placental insufficiency | Newborn (often SGA): hypoglycemia, hypothermia, polycythemia, hypocalcemia |
| Oligohydramnios | AFI 5 cm or less or deepest pocket below 2 cm; causes include ROM, renal anomalies, placental insufficiency | Cord compression (variable decelerations); newborn: pulmonary hypoplasia, renal anomalies, positional deformities |
| Polyhydramnios | AFI 24 cm or more or deepest pocket 8 cm or more; diabetes, fetal GI obstruction (esophageal or duodenal atresia), CNS anomalies, multiples | Mother: uterine atony and PPH, cord prolapse at ROM. Newborn: excess oral secretions suggest esophageal atresia; confirm passage of an orogastric tube |
Rh Alloimmunization
An Rh(D)-negative patient exposed to Rh-positive fetal cells may form anti-D antibodies that cross the placenta in later pregnancies, causing hemolytic disease of the fetus and newborn (anemia, hyperbilirubinemia, hydrops). Prevention: antibody screen, RhIG 300 mcg at about 28 weeks, after sensitizing events (bleeding, trauma, amniocentesis, external version, loss), and within 72 hours of birth if the newborn is Rh-positive. A Kleihauer-Betke or flow cytometry test quantifies fetomaternal hemorrhage. Once a patient is sensitized (positive anti-D titer), RhIG no longer helps; the fetus is followed with middle cerebral artery Doppler for anemia, and the newborn needs a direct antiglobulin (Coombs) test, hemoglobin, and early bilirubin monitoring.
What to Remember for the Exam
- After GDM: 75-g, 2-hour OGTT at 4–12 weeks postpartum, then every 1–3 years.
- Preeclampsia can first appear postpartum; severe-range BP is treated within 30–60 minutes.
- Infant of HBsAg-positive mother: hepatitis B vaccine plus HBIG within 12 hours; breastfeeding is fine.
- Adequate GBS prophylaxis = penicillin, ampicillin, or cefazolin 4 hours or more before birth.
- Opioid use disorder in pregnancy: MOUD, not withdrawal; breastfeeding supported on stable treatment.
- Polyhydramnios: think atony for the mother and esophageal or duodenal atresia for the newborn.
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