Ages Eligible for Study: 13 Years and older
Genders Eligible for Study: Female
Accepts Healthy Volunteers: No


Inclusion Criteria

  1. Women with chronic hypertension in pregnancy with new or untreated chronic hypertension, blood pressure 140-154 systolic or 90-99 diastolic OR known chronic hypertension on monotherapy and taking any antihypertensive and blood pressure ≤150/95 (including those with blood pressure <140/90);
  2. Singleton; and
  3. viable pregnancy <18 weeks of gestation.

Exclusion Criteria

  1. Blood pressures prior to randomization ≥155 systolic or ≥100 diastolic (with or without treatment);
  2. Patients currently treated with >1 antihypertensive medication (more like to have severe chronic hypertension);
  3. Multi-fetal pregnancy;
  4. Known secondary cause of chronic hypertension;
  5. High-risk co-morbidities for which treatment may be indicated:
    • Class D or higher diabetes mellitus
    • Chronic kidney disease – including baseline proteinuria (>300mg/24-hr, p/c ratio >0.3, or persistent 1+ proteinuria*) or creatinine >1.2. *If a dipstick value at screening is more than trace, a clean catch or catheter urine should be obtained and re-tested by dipstick. If this shows trace or absence of protein, the patient is included. If it again shows 1+ protein, the patient is excluded until a 24-hr urine <300mg/24hr or p/c ratio is <0.3.
    • Cardiac disorders: cardiomyopathy, angina, CAD
    • Prior stroke
    • Retinopathy
    • Sickle cell disease;
  6. Known major fetal anomaly;
  7. Known fetal demise;
  8. Suspected IUGR;
  9. Membrane rupture or planned termination prior to randomization;
  10. Plan to deliver outside the consortium centers or unlikely to follow-up in the opinion of study staff or previous participation in this trial;
  11. Contraindication to labetalol or nifedipine (e.g. know hypersensitivity); and (12) Current substance abuse or addiction (cocaine, methamphetamine) *The minimum age varies by center