When I was newly pregnant, I had a miscarriage scare. I worried for the next few months and breathed a giant sigh of relief when I started the second trimester. Then a neighbor went into early labor and I had a new worry. So how early can a baby be born?

Modern medicine is amazing, especially when it comes to treatments for premature babies. It is nothing short of miraculous, and the advances in understanding have drastically improved the outcome of extremely early deliveries. Here is the current reality:

Baby Born at 22 weeks

Babies are unlikely to survive at this stage. There is a 14.8% chance of survival for babies born at 22 weeks, but even then, half of these babies have brain damage. As of now, the earliest a baby can be born is 22 and a half weeks. No baby has been successfully delivered before this time. Most babies born at 22 weeks weigh about one pound and do not have functioning lungs, since their airways are not fully developed.

Baby Born at 23-24 weeks

Survival at this stage depends on birth weight and health at birth: 25% of babies survive when born at 23 weeks, and 42 percent survive in the 24th week. Babies born at 23 or 24 weeks depend on a ventilator and around-the-clock care to survive. They have very little body fat and muscle tone. Since they cannot suck and breathe at the same time, they must be fed through an IV.

Baby Born at 27 weeks (Extremely early)

90% of babies born who are treated in the neonatal intensive care unit (NICU) will survive to at least one year of age. NICUs are equipped with everything a baby born early might need, such as incubator, overhead heater, all kinds of monitors, feeding pump, IV, and ventilators.

Babies this age deal with the constant threat of hypothermia, low blood sugar, low blood pressure, and infection. They also need help breathing. Though survival rates are extremely high, 25 percent of surviving babies have severe or moderate disabilities, ranging from hearing loss and vision problems to learning disabilities.

Baby Born at 28-31 weeks (Very early)

Premature birth at born at 27 weeks will still require specialized care in the NICU. While they are much stronger than extremely early babies, they are still at risk for hypothermia, low blood sugar, and infection.

But not all hospitals are equipped with NICUs. Most have a local neonatal unit (LNU) to handle the needs of a stronger but still early baby.

In the absence of a medical problem, babies are healthier the longer they stay in utero. But long-term outcomes are reassuring: only a few of the babies born in weeks 28 and 29 will have problems with eyesight, hearing, movement, or brain development.

Baby Born at 32-33 weeks (Moderately early)

Some babies born at 32 weeks are able to stay with their mothers in a transitional care ward but they still require special care because of problems with breathing, feeding, and infection. Most babies born at this stage weigh between three and four pounds, and are as long as babies at full term (18-19 inches).

Gaining weight is the primary concern for babies born before 34 weeks, since they do not have sufficient body fat to maintain a healthy body temperature. Babies born in this range are also at risk of infection and may have trouble sucking.

Baby Born at 34-36 weeks (Early)

Babies born at 34 weeks are incredibly small and strong. They may not need any special treatment or they may need some transitional care depending on how well they are feeding, regulating blood sugar, and blood pressure.

In the last few decades, babies have been considered term at 37 weeks. Since then, many people, including medical professionals, have assumed that not much development occurs after. But new data shows that there is a lot of essential work done in the last few weeks of pregnancy. For example, a baby’s brain at 35 weeks weighs only two-thirds of what it will weigh at 39-40 weeks. Because being born before 39 weeks isn’t without risks, the American Congress of Obstetricians and Gynecologists has redefined the meaning of “term:”

Baby Born at 37-38 weeks (Early term)

Though babies born at 37 weeks were considered full term for many decades, doctors now know that some important development still takes place in weeks 37 and 38. Findings show that babies delivered electively at 37 weeks are four times more likely to spend time in the NICU and have respiratory issues than babies born at 39 or 40 weeks. Babies at this stage still undergo brain, lungs, and liver development.

Baby Born at 39-40 weeks (Full term)

Babies born at full term are significantly better off than babies born earlier. They breathe better, have gained enough weight to better regulate body temperature, and can suck, swallow, and stay awake long enough to eat.

In my experience, late babies are calmer babies as their nervous systems have had longer to develop. All four of my babies were born after their due date and all of my sister’s babies were born before. Those sweet, early babies are more than fine today. They just needed more patient, attentive care in that first month compared to their cousins.

How to Minimize Your Chances of Premature Birth

Still wondering, “How early can you have a baby?” In short, the odds are exponentially better if you deliver after 27 weeks, but a small percentage of babies survive between 22-26 weeks. Rates of survival without complications increase with each week of pregnancy.

So how can you minimize your chance of premature birth? Here are a few tips:

• Start your pregnancy at a healthy weight and gain the recommended amount of weight during pregnancy.
• Avoid smoking, drugs, and alcohol while pregnant.
• Do everything you can to reduce stress in your life.
• Get vaccinated and protect yourself from infections.
• Visit your doctor for treatment of chronic health problems.
• Wait 18 months to get pregnant between children.
• Avoid heavy lifting and intense physical activity, especially in the later weeks of pregnancy.

Have you delivered a pre-term baby?