Premature Birth: Risk Factors, NICU Levels and What Parents Should Know

A premature birth is any birth that happens before 37 completed weeks of pregnancy. A full-term pregnancy usually lasts about 40 weeks. Almost 1 in 10 babies born in the United States arrive early, and the earlier a baby is born, the more medical support they may need at first.

This page covers the main risk factors linked to preterm birth, what the different levels of newborn intensive care mean, what a NICU stay is generally like, and where to find more support. It does not replace a conversation with your own doctor or midwife.

Urgent concerns linked to Premature Birth

Contact your health care provider immediately, or go to the nearest emergency room, if you notice any of these signs before 37 weeks of pregnancy:

Contractions that happen every 10 minutes or more often
Fluid leaking or bleeding from the vagina
A feeling of pressure low in the pelvis
A low, dull backache that doesn’t go away
Cramps that feel like menstrual cramps
Abdominal cramps, with or without diarrhea

Don’t wait to see if symptoms pass on their own. Early evaluation can make a real difference in what happens next.

Medical Disclaimer: This page is for general education only. It is not medical advice, diagnosis, or treatment, and reading it does not create a provider-patient relationship. Talk with a licensed healthcare provider about your specific pregnancy. If you are having a medical emergency, call 911 or go to the nearest emergency room. See our full Medical Disclaimer.

What Raises the Risk of Preterm Birth

Some risk factors can be changed, and some can’t. Having one or more of these does not mean preterm birth is certain — it means it’s worth talking through with your care team, ideally at a prenatal visit.

Pregnancy History

Having delivered preterm before, or having had preterm labor before
Being pregnant with twins, triplets, or more
A pregnancy conceived through assisted reproductive technology
Less than 6 months between a previous birth and the start of this pregnancy

Physical and Medical Factors

A short cervix, or a cervix that shortens earlier than expected in pregnancy
Certain anomalies of the uterus or cervix
High blood pressure or preeclampsia
Urinary tract infections, sexually transmitted infections, or vaginal infections such as bacterial vaginosis
Vaginal bleeding during pregnancy
Placenta previa (when the placenta covers part or all of the cervix)
Certain developmental differences in the fetus
Being underweight or having obesity before pregnancy

Lifestyle and Other Factors

Smoking or using certain substances during pregnancy
Limited or delayed prenatal care
High stress, which researchers continue to study as a possible contributing factor

Some of these factors, like smoking or getting to prenatal visits, are things you and your provider can work on together. Others, like a uterine anomaly or a multiple pregnancy, are not something you caused and are not something you can change. Either way, your provider is the right person to help you understand your own level of risk.

Points to verify for Premature Birth

Do any of my personal or pregnancy health details put me at higher risk for preterm birth?
Should my cervical length be checked, and if so, when?
What symptoms should prompt me to call you right away versus wait for my next visit?
If I go into labor early, is there a hospital nearby with the level of newborn care my baby might need?
Are there steps I can take now, such as quitting smoking or treating an infection, that could lower my risk?

Understanding NICU Levels of Care

Not every hospital nursery offers the same level of care. Hospitals are generally organized into four levels, based on how much specialized support a newborn might need. Ask your provider which level of care your delivery hospital offers, especially if you’re considered higher risk for preterm birth.

Level I — Basic newborn care: For healthy, full-term babies. Staff can resuscitate a baby at delivery and stabilize an infant who needs more help before transferring them to a higher-level hospital.
Level II — Special care nursery: For babies who are moderately preterm or need extra support, such as help with feeding, temperature regulation, or short-term breathing assistance, without needing a full intensive care unit.
Level III — Neonatal intensive care unit (NICU): For babies born significantly preterm or who are seriously ill. This level typically includes ventilators, specialist physicians, and advanced imaging, and can handle many complications without transfer.
Level IV — Regional NICU: The highest level of newborn care. In addition to everything a Level III unit offers, these centers typically provide on-site surgery, including for complex conditions, and often serve as a referral center for an entire region.

If you’re identified as high-risk for preterm delivery before your baby is born, your provider may recommend delivering at, or transferring to, a hospital with a higher level of neonatal care already on-site. This is often safer than transferring a newborn after birth.

What to Expect During a NICU Stay

Every NICU stay is different, and length of stay depends on how early a baby was born and what health needs they have. In general, families can expect:

A team of neonatologists, nurses, and specialists monitoring your baby closely
Equipment that may look intimidating at first, such as monitors, feeding tubes, or breathing support — all used to help your baby grow and stabilize
Encouragement to be involved in your baby’s care, including skin-to-skin contact (sometimes called kangaroo care) when your baby is stable enough
Regular updates from the care team, and the chance to ask questions at any time
A gradual transition as your baby reaches milestones like maintaining their temperature, feeding on their own, and breathing without support

It’s common for parents to feel overwhelmed, anxious, or a mix of both hope and fear during a NICU stay. Hospital social workers and NICU staff can often connect you with support resources, including other parents who have been through it.

Putting Premature Birth information into practice

If you notice any warning signs above, call your provider or go to the emergency room right away — don’t wait.
Ask your provider directly whether your pregnancy is considered higher risk for preterm birth.
If so, ask which nearby hospitals offer the level of newborn care your baby might need.
If your baby is admitted to a NICU, ask the care team to walk you through what level of care they’re providing and what the next steps or milestones look like.
Lean on hospital social workers, lactation consultants, and support groups — you don’t have to navigate this alone.

What remains uncertain about Premature Birth

Some situations call for closer monitoring or a different conversation with your care team. Multiple pregnancies (twins or more), a prior preterm birth, a known short cervix, or a diagnosed uterine anomaly are all reasons your provider may recommend additional visits or testing. Pregnancies conceived through assisted reproductive technology also carry a higher average risk of preterm birth, which is worth discussing with a maternal-fetal medicine specialist if that applies to you.

This page does not cover every possible risk factor, every treatment option for preventing preterm labor, or the specific policies of any individual hospital or NICU. Guidance also continues to evolve as research advances. It is a general educational overview, not a personalized risk assessment or a substitute for the ongoing care of your OB provider.

Common questions about Premature Birth

What counts as a premature birth?

Any birth before 37 completed weeks of pregnancy is considered preterm. Babies born earlier in that range generally face more health risks than those born closer to 37 weeks, though every baby is different.

Can premature birth be prevented?

Not always. Some risk factors, like a multiple pregnancy or a uterine anomaly, can’t be changed. Others, like treating an infection or stopping smoking, are things your provider may be able to help you address. Ask your provider what, if anything, applies to your situation.

What’s the real difference between Level II and Level III NICU care?

Level II special care nurseries generally handle babies who need extra support but aren’t critically ill, such as help with feeding or short-term breathing assistance. Level III NICUs are equipped for babies who are more significantly preterm or seriously ill and may need ventilators or advanced specialist care.

How long will my baby stay in the NICU?

There’s no single answer — it depends on how early your baby was born and what health needs they have. The care team can give you a general sense of what to expect and will update you as your baby reaches key milestones.

Educational Disclaimer

This article is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. It does not predict any individual’s risk of preterm birth, recommend a specific hospital or NICU, or cover every possible complication of prematurity. Always consult a qualified health care provider about your specific pregnancy and any concerns about preterm labor.