GG5: a 「pregnancy [maternity] checkup.

We use antenatal.

@@ -15,0 +16 @@
+<gloss>pregnancy checkup</gloss>

https://medlineplus.gov/prenatalcare.html
Prenatal care is the health care you get while you are pregnant. It includes your checkups and prenatal testing. 

妊婦健診	26233
周産期医療 33710 <-- perinatal care
妊婦管理	918
出産前ケア 39　(more common on google than this suggests, but not standard)
出生前管理	85
胎児ドック	220 fetal checkup. 

https://eow.alc.co.jp/search?q=妊婦健診
prenatal care（出産前の）〔【参考】maternal care〕
prenatal checkup

Some other suggestions (low ngrams...)
https://eow.alc.co.jp/search?q=妊婦管理
maternal care《医》（母体に焦点を合わせた）〔【参考】prenatal care〕
適切な妊婦管理
appropriate prenatal care

Commonly glossed as "prenatal care" (or checkup).
https://context.reverso.net/translation/japanese-english/妊婦健診

A different, but-not-terribly-common gloss(professional translations of specialized vocab):
https://www.jsicm.org/pdf/yougo220209.pdf
出生前管理

We currently have a term glossed "prenatal care" (胎教), which is not "prenatal care" in any common sense of the word.  It's the only entry we have, so I went looking for the "correct" one...

I think there is no perfect term for "prenatal care" in Japanese, because the Japanese system wraps pre/post-birth care up as a single concept (i.e. perinatal care).  The core of "prenatal care" seems to me to be regular medical checkups, which is this term.  "prenatal care" also includes screening (出生前診断).  If you want a more useful term in Japanese, you want perinatal care (周産期医療). 

This is the only entry I think "prenatal care" can be legitimately placed on without introducing confusion, so I would prefer to xref the "missing" parts from here.

If you search "prenatal care" "tokyo", visit various clinics' English pages, find "prenatal care", switch languages to Japanese, you'll find that "prenatal care" is common in English, but the Japanese versions are all over the place. This just isn't a "standard" category like in English. "検診・胎児ドック・Prenatal Care" was a top-level menu on one site, for example.

I think antenatal is British? Never heard of it...

https://en.wikipedia.org/wiki/Prenatal_care
Prenatal care, also known as antenatal care, is a type of preventive healthcare. It is provided in the form of medical checkups, ...