Though my wife's two pregnancies, I've struggled to describing how much time has passed. Usually, I just revert to just saying how many months she's been pregnant, but in English there are other ways of measuring time in relation to pregnancy that are both more and less precise. I'll list these from least to most controversial (in my mind).

Months - I usually use this form of measurement, because I feel the least awkward about it. Saying 妊娠8ヶ月 feels alright to me, but is this a normal way to phrase it?

Weeks - Is it normal for a Japanese person to refer to how long an individual has been pregnant in the number of weeks? (i.e. She's 34 weeks pregnant) For some reason, saying something like 妊娠34週 just feels weird and clunky to me.

Trimesters - Let me define what I mean for any Japanese people unfamiliar with the concept. In American English, and likely for all English speakers (though I am not sure), a pregnancy is divided into three parts called trimesters. The first trimester is from conception to 3 months pregnant, The second trimester is 4-6 months pregnant, and the third trimester is from 7 months pregnant to birth. Using this unit of measurement, an English speaker would say something like: She's in the third trimester.

Unfortunately, trimester also refers to a school year divided into three parts rather than the standard two. This makes things harder for me to research, and I have never been able to refer to find a satisfactory answer. My way around this is to say:


However, that just feels kind of awkward to me, so I defer to just saying how many months pregnant she is. I can't but help but feel like I'm missing something here.

From what I can tell, the concept of trimesters doesn't exist. Is that really the case, or is there another way that pregnancy is measured that I'm just not aware of?

  • 4
    👶 2人目できはったん?おめでとう~! 今8か月?楽しみね!^^
    – chocolate
    Commented Jan 29, 2021 at 15:58
  • ありがとう!あと一週間で8ヶ月。予定日は3月9日が前回1週早かった。今回はどうやろうね。
    – ajsmart
    Commented Jan 30, 2021 at 3:37

1 Answer 1


I'd say ヶ月 is the most common. 初期、安定期、臨月 etc. is pretty common, too, but it implies pregnancy is the main theme of that conversation (as opposed to just mentioning it in passing).

If you say 週 one would assume you are discussing medical topics (it'd be a tad odd if you use it outside of that context).

  • Are 初期、安定期 and 臨月 the Japanese equivalent of trimesters?
    – ajsmart
    Commented Jan 30, 2021 at 3:38
  • @ajsmart I don't think so. My dictionary says the terms are the early days; the stable days after about four months; and the last month, respectively.
    – Ragaroni
    Commented Jan 30, 2021 at 14:21

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