Signs of early labor, before the 37th week of pregnancy, may be more subtle than dramatic, doctors say.

“It’s not necessarily even painful,” says Dr. James Marquardt, an obstetrician/gynecologist in Midlothian, Va. Some tips:

Be aware of contractions. They can feel as if your abdomen is tightening like a fist every 10 minutes or less, rather than anything sharp or painful.

Pay attention to back pain ... A dull ache in the lower back can be a sign of trouble, whether the discomfort is constant or comes and goes. You also may feel more pressure or fullness in your pelvic area, as if your baby is pushing down.

... and cramping. Regular abdominal cramps that feel like a menstrual period or gas pains aren’t a normal discomfort of pregnancy.

Don’t wait for your water to break. Even with full-term births, only about one in four women will experience the stereotypical gush of water before labor begins. But increased vaginal discharge — watery, mucus-like or bloody — can indicate preterm labor.

Stay in tune with your baby. A decrease in typical fetal movement may need attention.

Err on the side of caution. Call your doctor with concerns and follow advice, which can include resting on your left side or drinking two or three glasses of water or juice to see if you feel better. If symptoms worsen or return, or if there’s any doubt in your mind, ask for a checkup or head to a hospital.

Report any problems. Tell your doctor about abnormal symptoms even if they go away. Also share any history of preterm birth, which is a risk factor for early labor in subsequent pregnancies.