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. Severe hypertension including 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:

      - Diabetes mellitus diagnosed at age ≤10 years or duration of diagnosis ≥20 years

      - Diabetes mellitus complicated by end organ damage (retinopathy, nephropathy,
      heart disease, transplant)

      - Chronic kidney disease - including baseline proteinuria (>300mg/24-hr,
      protein/creatinine 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. If a
      p/c ratio is >0.3, the patient may be included if a 24-hour urine is < 300 mg.

      - 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 and nifedipine (e.g. know hypersensitivity);

12. Current substance abuse or addiction (cocaine, methamphetamine)

13. Participation in another trial without prior approval (CHAP participants will not be
   enrolled in other trials without prior approval by protocol committee)

14. Physician or provider refusal

15. Patient refusal *The minimum age varies by center