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Although “preterm” and “premature” are used interchangeably to describe infants born before 37 gestational weeks, there are slight differences between the two terms that are well worth noting.

I might not have ever thought twice about it, but back in the NICU, I was talking to one of our clinicians and tried reaching for a word to describe, you know, babies who aren’t premature, you know, the eight-nine percent. It was on the tip of my tongue to say “regular babies,” but I couldn’t quite bring myself to say it. “Mature babies” didn’t sound right either, because it sounded like a value judgement. The neonatologist sensed my mental hiccup, and gently suggested I use the term “term” to describe babies who were carried fully to term, and “preterm” to describe infants who were delivered a little bit (or a lot of a bit) early.

Since then, I’ve come to favor the word “preterm” as opposed to “premature” when I write about the topic, but I will still use “premature” for random strangers at the mall. That’s why I thought it might be helpful to note the differences between the two words and their usage.


Clinical, academic, and non-judgemental, “preterm” describes infants who were born before 37 weeks. As stated above, the opposite of “preterm” is “term,” which is a far preferable dichotomy than “premature” and “mature.”

When to use it: When discussing the topic of prematurity with people who know about prematurity–doctors, nurses, specialists, etc., but also family and friends who are following your infant’s progress with well-wishes and prayers. Definitely use it in email updates; definitely use it in blog posts in which you reference a lot of research statistics.

When not to use it: When you’re trying to make an emotional connection with your H.R. representative regarding maternity leave and short-term disability. “Preterm,” is this context, feels like “other people’s problems.”


Popular, familiar, and emotionally evocative, “premature” describes infants who were born before 37 weeks.

When to use it: When you’re talking about the topic with the general public (many journalists favor the term when writing for a large audience), or when you’re talking to your childless Facebook friends. Unlike the word “preterm,” “premature” is more likely to evoke images and stories of “small babies” and all the emotions that go with it.

When not to use it: When you’re talking to your health care team–“preterm” just sounds more smart-ish. Also, avoid using “premature” if you don’t want to be held up by break-room conversations (seriously, everyone who knows someone who’s had a “premature” infant will tell you about it).

Bonus: Preemies

A warm fuzzy, cutesy term with beau-coup currency in popular discussions of prematurity, but a term which can also obscure the serious, medical complications of preterm deliveries.

When to use it: When talking about infants and children. Use it in the past tense (was a preemie) if a particular child is close to or has already closed their developmental gap.

When not to use it: When talking about adults. It’s infantalizing. But if an adult wants to use the term to describe themselves and their medical history, then follow their lead.