Period or pregnancy? How to tell if sore breasts mean you're expecting

Wondering what could be the cause of your breast discomfort or tenderness?
Written by
Molly McLaughlin
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Last updated on
June 3, 2024
min read
Period or Pregnancy? How to Tell If Sore Breasts Means You're Expecting | Kin Fertility
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Wondering what could be the cause of your breast discomfort or tenderness? Throughout the menstrual cycle, the body goes through a series of dramatic changes as it prepares for ovulation and potential pregnancy. For many women, a feeling of soreness in the breasts, also known as mastalgia, is common during the luteal phase, as well as during early pregnancy.

Minor breast discomfort and swelling within the few days before the start of your period is considered normal, but if you're experiencing persistent pain it is worth checking in with your doctor. In a small number of cases, breast pain has been linked to cancer, but a painless, hard-edged mass is more often a symptom.

There are a bunch of other causes of mastalgia, which we'll explain below. While a positive test result is the most reliable indicator of pregnancy, there are also specific physical signs (including breast soreness) to look out for as early signs of pregnancy.

Is breast tenderness an early sign of pregnancy?

Sore breasts are commonly reported as the first sign of pregnancy [1]. This is mainly due to hormonal fluctuations, particularly the increased levels of oestrogen and progesterone in the body after conception. As mentioned above, because breast tenderness can also occur during the luteal phase before your period, it is not a definitive indicator of pregnancy.

The menstrual cycle

Despite the fact that it happens every month, it can be tricky to keep track of what's going on with our bodies. If you need a refresher, the menstrual cycle begins on the first day of your period, which lasts between 2 and 7 days for most people.

During the beginning of the cycle, the uterus sheds its lining if there isn't a fertilised egg ready to implant. (On the other hand, if there is a fertilised egg present, a placenta begins to form and produce human chorionic gonadotropin as the pregnancy progresses — this is the substance detected by a pregnancy test).

After your period ends, the body starts getting ready for another possible pregnancy by thickening the lining of the uterus again. During the middle of your cycle, usually around day 14, one of your ovaries releases an egg. This is called ovulation, but if the egg isn't fertilised within about 24 hours, it dissolves.

Towards the end of the cycle, breast tenderness and other pre-menstrual symptoms (PMS) kick in as the uterine lining is shed and expelled in the form of a period. The length of your cycle can vary, but it's generally said to be around 28 days.

What kind of breast soreness indicates pregnancy?

More research is needed to conclusively distinguish between PMS-related tender breasts and pregnancy-related breast pain. Anecdotally, pregnancy symptoms can occur as early as 1-2 weeks after conception, which can be before you would typically expect to experience PMS.

The breast soreness identified as an early pregnancy symptom is often described as more intense or pronounced compared to the usual premenstrual breast tenderness, too. Breast soreness that persists for several weeks or even months is obviously more likely to be linked to pregnancy, as PMS symptoms tend to abate after a couple of days with the onset of the period.

Along with general breast soreness, you may notice changes in your nipples during pregnancy. They may become more sensitive, tingly, or darkened in colour as the pregnancy progresses.

Why are breasts sore during pregnancy?

Sore breasts are one of the most common (and painful!) pregnancy symptoms. The rise in oestrogen and progesterone levels in the pregnant person's body is needed to stimulate the growth of milk ducts and the expansion of breast tissue in preparation for breastfeeding.

Unfortunately, the resulting increased blood flow, swelling and increase in breast size and sensitivity can result in soreness and discomfort as the skin and tissue stretch to accommodate the milk ducts.

How to treat sore breasts

Whether soreness is due to pregnancy, your period or something else, there are a couple of things you can do to relieve the pain. Wearing a well-fitting and supportive bra can help reduce breast movement and provide a bit of comfort. Applying a warm compress or taking a warm shower can also help relax the breast tissue and relieve soreness. (If the soreness is due to inflammation, a cold compress might be a better choice).

Some women find that reducing their intake of caffeine, salt, and fatty foods can help alleviate the symptoms of pre-menstrual syndrome, but more research is needed to confirm dietary changes as an effective treatment for PMS [3].

If you're noticing dry or itchy nipples are contributing to breast soreness, Kin’s Nipple Balm relieves sore nipples, by moisturising and preventing chafing. It can be used before birth as well as during breastfeeding.

What are other pregnancy symptoms after ovulation?

There are a lot of big adjustments happening during the first trimester, some of which you may be able to see and feel quite early on. The combination of these symptoms can provide an indication of whether or not you are pregnant.

Implantation bleeding

While a missed period is the most obvious sign of pregnancy, some women experience light spotting or irregular bleeding during early pregnancy as well. This is called implantation bleeding and happens when a fertilised egg implants itself into the lining of the uterus.

Implantation bleeding usually occurs around 6-12 days after fertilisation, which is typically also around the time of your expected period. However, not all women experience it, so by itself, bleeding isn't a total giveaway.

Although the timing may be similar to a period, implantation bleeding is generally lighter and shorter in duration compared to a regular period. The bleeding is often described as pale pink or brown in colour, in contrast to the darker colour of a normal period.

Some people report the bleeding is light enough to require only a panty liner as opposed to a pad or tampon. Mild cramping or abdominal discomfort can also accompany pregnancy-related bleeding, but it is usually less severe than PMS cramps.

Basal body temperature plateau

You might have heard the term basal body temperature plateau or BBT in reference to fertility. A BBT plateau refers to a period of sustained high temperatures and is used as an indicator of ovulation. The BBT is the body's lowest resting temperature, usually measured immediately when you wake up in the morning.

A BBT plateau refers to a period of several consecutive days with sustained higher temperatures compared to the pre-ovulatory phase. This sustained increase in temperature usually occurs after ovulation and can continue until the start of the next menstrual period or, if pregnancy occurs, throughout the early stages of pregnancy. Because of this, a BBT plateau is not a reliable indicator of successful fertilisation or implantation.


Approximately two-thirds of pregnant people experience some form of nausea or vomiting in the early stages of the pregnancy [2], commonly known as morning sickness. Nausea and vomiting typically commence around week 8 of pregnancy and begin to fade after 12 or so weeks.

Morning sickness can occur at any time of the day or night and symptoms can vary from mild to severe. If you feel consistently nauseous and there's a possibility you might be pregnant, taking a pregnancy test is recommended.

Mood swings

Mood swings during pregnancy are primarily attributed to the hormonal changes in the body as it adapts to support a developing foetus. Additionally, the first trimester often brings fatigue, nausea, and various physical discomforts, contributing to irritability and frustration.

Pregnancy can also make women more sensitive to stress and emotional triggers, so everyday events that might not have had a significant impact before pregnancy can now have a more pronounced effect on mood and emotional well-being. If mood swings begin to impact your life make sure to seek support from family and friends, as well as professional help if required.

Increased sense of smell

An increased sense of smell is often experienced as one of the early pregnancy symptoms. It is thought that the changes in levels of hCG may enhance the senses through increased blood flow. Pregnant women may also develop aversions to specific odours linked to morning sickness or nausea in the first trimester.

Alongside a pregnancy test or a missed period, there are some subtle changes in your body that can give you a hint about whether or not you're pregnant. These early pregnancy symptoms can help give a fuller picture of what's going on with your body so you can consider next steps.

Photo credit: Getty Images

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