Inclusion Criteria:

   1. Women with chronic hypertension in pregnancy with new or untreated chronic
   hypertension, blood pressure 140-159 systolic or 90-104 diastolic OR known chronic
   hypertension on monotherapy and taking any antihypertensive and blood pressure
   ≤159/104 (including those with blood pressure <140/90);

   2. Singleton; and

   3. viable pregnancy <23 weeks of gestation.

Exclusion Criteria:

   1. Blood pressures prior to randomization ≥160 systolic or ≥105 diastolic (with or
   without treatment);

   2. Patients currently treated with >1 antihypertensive medication (more likely 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 C 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 (unless approved by the Clinical
   Coordinating Center) 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