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Before I started properly tracking my period, I had a number of late period freak-outs. Usually resulting in me awkwardly buying an unnecessary pregnancy test at the supermarket, only for my period to arrive a few days later.
Has this ever happened to you?
Late Period or Late Ovulation?
I later learnt that my period was never late, I had just ovulated late. If I had been tracking my cycle and observing the signs from my body, I would have been able to identify when I ovulated. If ovulation was later later in my cycle than usual I would have known to expect my period later.
You see, our menstrual cycle has two phases:
1. Follicular phase – from menstruation to ovulation we are in the follicular phase;
2. Luteal Phase – from ovulation to the start of the next menstruation we are in the luteal phase.
The only part of the cycle that can vary greatly in length is the follicular phase. Because there are many things that can delay ovulation (like stress and illness). Once you ovulate though, your luteal phase won’t really be any longer than 16 days. It can vary from 12 – 16 days in length.
The Follicular Phase of the menstrual cycle is the time from the first day of the period through to ovulation. Part of this phase is the menstruation phase, which is when the bleeding occurs. After the bleed is over, the follicular phase is the time when follicle stimulating hormone (FSH) is released, stimulating the growth of 5-20 follicles.
The developing follicles release a form of oestrogen called estradiol which stimulates the the lining of the uterus to grow and thicken. This is preparing for the possible implantation of an egg and subsequent growth of a baby.
The more estradiol produced, the thicker your uterine lining will be and the heavier your period will be, if there is no pregnancy.
Estradiol is also responsible for the production of cervical fluid. Cervical fluid is produced in the lead up ovulation and is a sign of fertility. Cervical fluid is designed to keep sperm alive inside the otherwise acidic vagina for up to 5 days. If you want to learn more about fertility signs, you can click this link to read my previous post What is Fertility Awareness.
The follicular phase culminates in one follicle (or two, in rarer instances) becoming dominant and then finally rupturing and releasing an egg – this is ovulation! Ovulation is triggered by the luteinising hormone (LSH).
“Ovulation is an all-or-nothing event. You cannot sort of ovulate. Your either ovulate or you don’t. Once you have ovulated, there is no going back. Your egg has been released, and it cannot be recalled…after ovulation, you will either be pregnant or you will get your period approximately two weeks later. There is no third option. It’s not possible to ovulate but then not be pregnant or get your period.”Lara Briden – The Period Repair Manual
Once ovulation has occurred, you then move into the luteal phase. Unlike the follicular phase, the luteal phase has a finite time span, dictated by the lifespan of the corpus luteum.
The corpus luteum is an incredible temporary endocrine gland. It forms that from the empty follicle left behind from ovulation.
The corpus luteum produces the very beneficial hormone progesterone, which is responsible for nourishing pregnancy, but also holds other benefits than just for pregnancy.
If pregnancy were to occur after ovulation, the corpus luteum would stick around, producing progesterone for three months. After this the placenta would take over this job.
If pregnancy does not occur after ovulation, the corpus luteum will only be around for a short period of time, around ten to sixteen days. After this, it will disintegrate, progesterone levels will drop and the uterine lining will begin to shed. And just like that, the cycle has come full circle and we are back at menstruation.
Interestingly, progesterone causes a rise in basal body temperature, which is why we can use our basal body temperature to identify when we ovulate! The temperature rises after ovulation and stays in this higher range while the corpus luteum is still producing progesterone. As soon as the corpus luteum disintegrates and stops producing progesterone, the temperature drops again and the next period starts.
The key takeaways are:
> while the follicular phase, from menstruation up until ovulation, can vary in length, once ovulation has happened a period will arrive within the next two weeks (unless pregnancy has occurred).
> If you know when you ovulate, you can know when to expect your period.
> Unless pregnant, your period won’t be late. It may be later than expected based on previous cycles but the reason will be due to ovulation being late/delayed.
From a practical sense, as an example, this is relevant to me at the moment because I’m currently on Day 25 of my cycle and I haven’t yet identified ovulation! If I wasn’t tracking my cycle, I’d be expecting my period to arrive within the next week and when it didn’t I’d be freaking out and probably off to waste money on a pregnancy test.
Since I know I haven’t ovulated yet, I’ll be cool as a cucumber when my period doesn’t arrive next week.
1. Period Repair Manual: Every Woman’s Guide to Better Periods – by Lara Briden;
2. All about the follicular phase of the menstrual cycle https://www.healthline.com/health/womens-health/follicular-phase
The Better Period
Ellie Heasman is a period blogger and founder of The Better Period. Ellie helps people on their journey to a better period through introducing them to the world of menstrual cups and period underwear, and sharing knowledge about the menstrual cycle and fertility awareness. You can join in the better period conversations on Instagram @thebetterperiod_ or find out more about Ellie here.