Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Call emergency services if you have:
Heavy vaginal bleeding
Severe or constant abdominal pain
An urge to push or a feeling that birth is happening
An umbilical cord or part of the baby visible at the vagina
Fainting, severe weakness, or difficulty breathing
Call emergency services, avoid eating or drinking, and follow the dispatcher’s instructions.
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Before 37 weeks, contact your maternity unit or obstetric service urgently if you have regular contractions, period-like cramps, new pelvic pressure, a persistent backache, vaginal bleeding, or watery fluid leaking from the vagina.
Also seek prompt assessment if your baby is moving less than usual.
Do not wait for your next routine appointment.
These symptoms may have causes other than labor, but they need assessment.
The article also says
If a cord is visible or felt, do not push it back inside.
Every sign above is quoted from the sofidex article on Preterm labor. If you are not sure, err upward — it is always reasonable to be checked.