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morning sickness
Conception Pregnancy Jan 14, 2021
3 Minutes

Is morning sickness the first sign/earlier than we thought?

New research (1) suggests that the onset of morning sickness could be as quick as eleven days after ovulation and fertilisation. That could be your first sign even prior or at the same time as a missed period! It also appears to start on average around a short three day window and seems to apply to the majority of women. This is much quicker and more precise than previously thought. Heres what we know: 

What the new stats say about morning sickness: 

This new research (1) appears that nearly 70% of women experienced some form of symptom as soon as 11 to 20 days post ovulation. Given most women experience their period 10 to 14 days after ovulation this could be a lot quicker than we had previously realised. 

When you ovulate appears to be key for understanding when you’re most likely to start morning sickness/nausea: 

The key difference with this new research is that it looks at the time from ovulation. Not the time from last period (which is initially how your due date is estimated). This is typically a much more accurate way to gauge. The reason being cycles can vary person to person and even month to month making it a much less reliable indicator. 

Click here for much more on ovulation and how to accurately gauge yours. 

Looking at onset of sickness from ovulation reveals that on average it starts much sooner than we had thought: 

It also on average seems to be most likely to occur within a three day window. It is also closely tied with the rise in the pregnancy hormone hCG. With 88% of women experiencing a rise within 8 to 10 days of ovulation (and subsequent fertilisation). Suggesting that this could be one of the earliest symptoms even prior to a missed period. 

hCG seems to be the key when it comes to morning sickness and the severity that we experience: 

The hormone that is most closely researched and linked with morning sickness is Human Chorionic Gonadotropin aka hCG. This is a pregnancy specific hormone that is produced by the outer cells of a fertilised embryo from the time it implants (4). It is also the hormone that pregnancy tests look out for. 

How hCG impacts the severity of your morning sickness and could even indicate whether you’re having a boy or a girl! 

Whilst other hormones are on the rise during pregnancy (progesterone and estrogen) the hormone that has been linked most closely to morning sickness is hCG. One of the reasons for this link is because typically it peaks at between 9-12 weeks, which is usually when most women feel at their worst. It has also been linked in higher concentration in women with molar pregnancies, with more than one fetus or while pregnant with a girl. Click here for much more.  All incidences where nausea and sickness have statistically been shown to be higher. (2, 3) 

Older women appear to experience symptoms slightly later: 

These are obviously averages and there are always individual differences but the statistics suggest that older women (+35yrs) tend to experience the onset of sickness slightly later in this band.

For much more about the clues morning sickness can give about your pregnancy click here. 

Or here for more on Hyperemesis Gravidarum the more severe form of morning sickness.

Finally – to understand accurately why it is crucial to know when you’re ovulating. Click here. 


2) Bustos M, Venkataramanan R, Caritis S: Nausea and Vomiting of Pregnancy – What’s new? Autonomic Neuroscience: basic and clinical: 2017 Jan: 202 62-67

3) Mitsuda N, Eitoku M, Suganuma N: Severity of Nausea and Vomiting in Singleton and Twin Pregnancies in Relation to Fetal Sex: The Japan Environment and Children’s Study (JECS): Journal of Epidemiology: 2019; 29(9): 340-346




This article is for informational purposes only. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. The information on this website has been developed following years of personal research and from referenced and sourced medical research. Before making any changes we strongly recommend you consult a healthcare professional before you begin.




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