Are there specific harmful effects of tocolytic therapy?

Yes. Tocolytics are drugs that are used to stop preterm labor. Terbutaline when used long-term can cause increased risk of heart attack and stroke in the mother. Magnesium can cause some muscle weakening in both mother and baby but may have a protective effect on the baby's brain. Indocin (indomethacin) can cause decreased amniotic fluid and premature changes in the blood flow through the baby's lungs.
Yes. Just recently, the fda removed its specific approval for the long-term use of terbutaline due to unacceptable side effects, which can include pulmonary fluid overload, cardiac problems, etc. Other medications are still used to treat pre-term labor, but in many cases, the benefits far outweigh the risks. Prematurity can lead to cerebral palsy, learning and motor developmental delays, etc.