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PMS and pregnancy
Summary
PMS and early pregnancy can feel remarkably similar - from mood swings and fatigue to bloating and breast tenderness - making those two weeks of uncertainty especially emotional. This article explores the hormonal overlaps between PMS and pregnancy, why symptoms can be confusingly alike, and how to tell them apart. It also explains how pregnancy affects PMS and PMDD, why symptoms may disappear during pregnancy, and what to watch for after birth.
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🌿 Key takeaways
PMS vs pregnancy symptoms: what to know
- PMS and early pregnancy share many symptoms because both involve elevated progesterone levels
- Nausea and morning sickness are typically a sign of pregnancy rather than PMS
- PMS symptoms resolve a few days after your period starts; pregnancy symptoms do not
- People with PMS and PMDD often find their symptoms improve during pregnancy due to more balanced hormone levels
- People with a history of PMS or PMDD are almost twice as likely to experience postpartum depression
- Not all PMS treatments are safe during pregnancy - always speak to a healthcare professional before making changes
What is PMS?
PMS (premenstrual syndrome) occurs in the days or weeks leading up to a period. While up to 75% of people with periods experience PMS symptoms, it is clinically defined as a range of physical, psychological, and behavioural symptoms that occur during the luteal phase - the two weeks before a period - and that disrupt normal daily life. Symptoms typically resolve a few days after the period arrives.
Physical symptoms include abdominal cramps, bloating, breast tenderness, headaches, backache, constipation or diarrhoea, fatigue and skin changes including oiliness or acne. Psychological symptoms include anxiety, sadness, depression and irritability. Behavioural symptoms include mood swings, brain fog and disrupted sleep.
We do not fully understand why PMS occurs, but it is thought to be linked to fluctuations in hormone levels during the luteal phase, or individual sensitivity to those fluctuations. During the luteal phase, progesterone levels are initially high, then both progesterone and oestrogen decrease until menstruation begins.
What is early pregnancy?
Early pregnancy can be a confusing term, particularly when it comes to calculating how many weeks pregnant you are. The number of weeks is calculated from the first day of your most recent period, so in reality, conception has not actually occurred for the first two weeks of the count, as the body is still preparing for ovulation.
Once an egg is released, fertilised and implants in the uterine lining, cells begin to grow that will eventually form part of the placenta. These cells start producing hCG (human chorionic gonadotropin) - the hormone detected by pregnancy tests. In the weeks that follow, early signs of pregnancy may begin to appear.
🧠 In simple terms: Week one of pregnancy is actually the week of your last period. By the time most people suspect they might be pregnant, they are typically already four to six weeks along by this counting method.
PMS vs pregnancy: what is the association and difference?
There are many perceived overlaps between PMS symptoms and early pregnancy symptoms. This is likely because of the high levels of progesterone experienced during the luteal phase of the menstrual cycle - whether a person is pregnant or not.
If you are not pregnant, progesterone and oestrogen drop at the end of the luteal phase and a period begins. If you are pregnant, those hormone levels remain high and the embryo continues to develop. Because one of the main theories for PMS is sensitivity to progesterone, high levels of this hormone during both the luteal phase and early pregnancy can trigger the same symptoms - regardless of whether the cause is a regular cycle or a pregnancy.
Another theory for PMS is an imbalance between progesterone and oestrogen. In pregnancy, oestrogen generally remains high to balance out elevated progesterone levels, which is not the case in PMS. This is why, theoretically, you cannot get PMS while pregnant - but you may well experience many of the same symptoms.
⚠️ Worth noting: The key difference is timing. PMS symptoms resolve within a few days of your period starting. If symptoms persist beyond your expected period date, it is worth taking a pregnancy test.
Symptom similarities: PMS and early pregnancy
Many symptoms can be a sign of either PMS or early pregnancy. Here are the most common ones that appear in both.
| Symptom | PMS | Early pregnancy |
|---|---|---|
| Mood swings | ✅ Yes | ✅ Yes |
| Pain and cramping | ✅ Yes | ✅ Yes (location may differ) |
| Spotting | ✅ Yes | ✅ Yes (implantation bleeding) |
| Appetite changes | ✅ Yes | ✅ Yes (how cravings present differs) |
| Breast tenderness | ✅ Yes | ✅ Yes |
| Increased urination | ✅ Yes | ✅ Yes |
| Bowel changes | ✅ Yes | ✅ Yes |
| Fatigue and disrupted sleep | ✅ Yes | ✅ Yes (often more pronounced) |
| Nausea / morning sickness | ❌ Not typical | ✅ Yes (from 4–6 weeks) |
⚠️ If you feel nauseous or sick: this is not typical of PMS and is usually a sign of pregnancy. If you experience nausea and do not expect it to be PMS-related, contact a healthcare professional.
How symptoms differ between PMS and pregnancy
While the symptoms may overlap, the way they present and how long they last are often different. Here is what to look out for.
Mood
During PMS, mood changes typically resolve once menstruation starts. In pregnancy, mood changes can last until you give birth.
Pain and headaches
Low oestrogen at the end of the luteal phase can cause menstrual headaches, as oestrogen has a pain-regulating effect. Headaches can also occur in the first trimester of pregnancy, but are more likely due to high oestrogen levels and increased blood volume. Joint and lower back pain is more typical of PMS and usually does not appear in the first trimester, though it may develop later in pregnancy as the bump grows.
Cramps
PMS cramps typically occur a day or two before a period, in the lower abdomen and sometimes with backache, and resolve within a few days of the period starting. Early pregnancy cramps feel similar and occur in the same area, but they tend to last for weeks or months rather than days.
⚠️ If early pregnancy cramps are accompanied by bleeding, seek medical attention immediately as this can be a sign of miscarriage.
Appetite changes
In the luteal phase, dropping serotonin and rising cortisol tend to drive cravings for sugary foods such as chocolate. In early pregnancy, appetite changes are more likely to be driven by shifts in the sense of smell and taste caused by rising hCG and oestrogen levels.
Urination
Increased urination can occur in both PMS and early pregnancy due to elevated progesterone. In both cases, if more frequent urination is accompanied by pain, nighttime urination, or blood in urine, this may indicate a UTI and should be investigated by a healthcare professional - particularly during pregnancy.
Bowel changes
Progesterone can cause constipation and digestive disturbances in both PMS and pregnancy. In PMS, these symptoms typically ease a few days into the cycle as progesterone drops. In pregnancy, they can last significantly longer.
Fatigue
Fatigue and disrupted sleep are common in both PMS and pregnancy. In PMS, these symptoms subside once the period starts. In pregnancy, elevated progesterone tends to make fatigue more pronounced, particularly in the first trimester, and it can persist throughout.
PMS treatment overview
There are many treatments for PMS, ranging from lifestyle changes to antidepressants. Because PMS is such a personal experience, so is the effectiveness of each approach - what works for some people will not work for others. For a full overview of currently recommended treatments, read Evelyn's articles on medicinal treatments, alternative therapies, supplements, and lifestyle adjustments.
⚠️ Important: Not all PMS treatments are safe during pregnancy. Always speak to a healthcare professional before making any changes to your routine, diet, supplement regime, or medication if you are pregnant or trying to conceive.
Relief for early pregnancy discomfort
Heat packs can help ease back and joint pain, as can a warm bath. Pregnancy support belts or slings can reduce pressure on the pelvis and back by supporting the bump. Specially shaped pillows can also help reduce pressure during sleep. As breasts change in size and weight during pregnancy, wearing a well-fitting, fully supportive bra is important.
Increasing dietary fibre and staying well hydrated can help with constipation, as can regular gentle exercise. For disrupted sleep, try an afternoon nap if possible, an early bedtime a few times a week, a warm bath before bed, and short sessions of mindfulness or meditation.
Will pregnancy affect my PMS?
Despite the many similarities between PMS and early pregnancy symptoms, people who experience PMS generally find that their symptoms improve during pregnancy. This is because, unlike in the luteal phase where oestrogen is falling while progesterone is high, during pregnancy both hormones remain elevated. This more balanced hormonal state is thought to reduce the impact of high progesterone levels - and therefore PMS-like symptoms.
However, after pregnancy, people with a history of PMS and PMDD are almost twice as likely to experience postpartum depression compared to those without. This may be due to the increased sensitivity of people with PMS and PMDD to hormonal fluctuations, and the abrupt drop in hormone levels after giving birth.
⚠️ After birth: If you have a history of PMS or PMDD and are postpartum, be aware of your increased risk of postpartum depression. Tell your midwife or GP about your PMS or PMDD history so they can monitor and support you appropriately.
Final thoughts
The symptoms of PMS and early pregnancy have a lot in common. Combined with the fact you will likely be waiting for a period in both circumstances, it can be genuinely difficult to tell the difference. Some pregnancy tests can detect a positive result two weeks post-implantation. If you have been experiencing symptoms for two weeks, they have not begun to subside, and your period has not arrived, it is probably time to take a test.
If you need further support, speak to a healthcare professional. If you do not feel able to talk to your GP, you can speak to a member of reception staff or the practice manager at your surgery.
Further reading
- Evelyn's guide on PMS, PMDD and seeing the GP
- Evelyn's guide on PMS, PMDD and the workplace
- Evelyn's guide on PMS, PMDD and relationships
Disclaimer: This content is for informational purposes only and is not intended as medical advice. Always speak to a qualified healthcare professional about any health concerns.
