35 wks preg. Have low period like pain.1cm dilatd 30% effacd at 34wk appt. Had celestone (betamethasone).Calld midwife said monitor few hrs since irregular. Advice?

Not uncommon. Unless you have a history of preterm birth or are having regular contractions every 5 minutes, what you're experiencing isn't necessarily abnormal and your cervix may continue to stay 1cm open and 30% effaced all the way up until term. Just stay in close contact with your midwife and report any worsening in your symptoms. You already had celestone (betamethasone) so you're in good shape. Good luck!