Eat a healthy diet (getting plenty of fruits, vegetables, whole grains, lean meats, etc.) and exercise if your doctor says it's OK.
Gain a healthy amount of weight (not too much or too little).
Protect yourself from infections (including Zika). Be sure to wash your hands well and often; don't eat raw meat, fish, or unpasteurized cheese; get any immunizations your doctor recommends; and use condoms to protect against STDs.
Reduce stress in your life (find help for financial troubles, get support from family or friends, etc.).
Other things that can increase a pregnant woman's chance of early labor include:
having had a recent pregnancy (less than 18 months ago)
difficult problems like unemployment, domestic violence, etc.
Talk to your doctor if you have any of these risks. In many cases, your doctor can help — such as offering progesterone shots to lower your chances of a preterm birth or prescribing antibiotics to fight infection.
Your doctor also can connect you with counselors or social workers who can help if you're dealing with addiction, financial troubles, or other problems.