Can Breastfeeding Cause An Irregular Menstrual Cycle?

The menstrual cycle is closely related to fertility, pregnancy, and even your breastmilk production, because of the close interplay between female hormones. This is why a change in hormone levels can cause the onset of ovulation just like it triggers lactation. Furthermore, when you breastfeed, you are telling your body that it can put your period on pause for weeks or months. Eventually, your period will return, but what is the normal time frame?

Will your menstrual cycle be like it was before pregnancy? What is normal or irregular? Can breastfeeding make your period irregular when it was normal before?

Keep reading to find out the answers to all these questions.

What Causes Periods To Stop?

During pregnancy, your body produces a hormone called prolactin, which promotes milk production but also assists in halting your menstrual cycle. When you begin breastfeeding, your body continues secreting prolactin. As long as the levels of prolactin remain elevated, you will not experience periods; and if you do, it will be a light flow. This also means that as soon as you wean your baby, your period will most likely return.

Why does this happen? During the first few months of life, your baby will probably exclusively drink breastmilk, unless you are using formula once in a while. This means your body will sense that it needs continued milk production. However, as your baby is introduced to solid foods and stops drinking so much breastmilk, the pituitary gland, which is responsible for prolactin, will produce less of the hormone.

So even if you are still sporadically breastfeeding, the low levels of prolactin can stimulate the restart of the menstrual cycle.

When Will My First Period Come After Pregnancy?

Because every woman’s body is different, there is no way to say exactly when your period will return. However, through scientific studies, it has been found that most women will return to menstruating about 45 to 94 days postpartum. One study, in particular, said that the average length of time is around 74 days after birth.

There are many factors that go into your period restarting. Sometimes, breastfeeding, birth control, and your own body’s internal clock can affect when you ovulate. According to professionals, the general time frame for periods to normalize can be anywhere between six months and two years.

What About Lochia?

Many new mothers get confused when they first experience something called lochia, a discharge that happens shortly after giving birth.

Lochia is not your period. It is heavy bleeding that occurs during the recovery period after birth and may last for several weeks (usually around 24-36 days). Any cramping you feel is the uterus shrinking back to normal size. While it may be difficult to tell the difference between lochia and menstruation, you will notice that lochia will lessen over time, becoming gradually lighter and lighter.

If your bleeding doesn’t stop or the flow doesn’t lessen, be sure to speak with a medical professional.

Does Menstruation Affect Milk Supply and Vice Versa?

A lot of women wonder if their periods are going to be different during breastfeeding and pre-pregnancy. Others are concerned about how menstruating could affect their breastmilk and vice versa. Your period will be irregular during breastfeeding, and you may experience irritability and moodiness, tenderness in the breasts, and bloating.

One thing to remember is that just because your period has restarted, it doesn’t mean your breastfeeding has to come to an end. It also doesn’t mean your milk will go bad during menstruation. If you find your baby is fussier around that time of the month, it is usually because milk production tapers off slightly (or can cease entirely) for the few days you have your period.

Once the period finishes, your milk supply will return to normal.

Precautions and Birth Control During Breastfeeding

There is one thing you need to be cautious about. The return of menstruation means you are once again fertile.

Some mothers use nursing as birth control through the “lactational amenorrhea method (LAM),” but that is only effective when a few conditions are fulfilled:

  • Your baby is younger than 6 months old
  • Your period has not started
  • You are exclusively breastfeeding and do not give your baby formula or a pacifier
  • You nurse your baby on demand

When you meet these conditions, there is very little chance you can get pregnant. That is why LAM is very effective. That said, once your period starts, you can no longer use LAM. You will need an alternate form of contraception.

Can Irregular Periods Mean Something Else?

When you are breastfeeding, your period may be longer or shorter than the average of 28 days. But if you were irregular before getting pregnant, chances are you will be irregular after too. Yet, there are many things that can affect the regularity of your cycle that goes beyond normal body functions.

If you are experiencing concerning symptoms, such as heavy bleeding, spotting, extremely long cycles, or abnormal levels of pain, you may want to visit your doctor. A medical professional can help rule out the following medical issues:

  • Extreme weight loss
  • Pelvic Inflammatory Disease (PID)
  • Ovarian cysts or Polycystic Ovary Syndrome (PCOS)
  • Uterine fibroids
  • Endometriosis


In short, breastfeeding can indeed cause an irregular menstrual cycle. However, you should know that while the changes in your cycle feel irregular, having a delayed return or even a change in menstrual flow is completely normal. Luckily, any complications you may have when your period returns usually clear up quickly on their own. Depending on how your period affects your body, you may choose to change how much and how often you breastfeeding your growing baby, but this too is entirely up to you!

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