The basic reason why pregnant women develop hypertension or Preeclampsia during pregnancy is abnormal development of the placenta. If there is not enough blood supply to the placenta, and hence the blood supply to the baby will be affected. If the placenta does not function properly there will be growth restriction, or stunted growth, in the baby. This might result in low birth weight in the baby. In certain cases if the mother has too many complications, an early birth might be advised which could result in a premature baby. For more information visit care.com