When Does Milk Start Leaking During Pregnancy?

A woman’s body undergoes a huge number of changes during pregnancy, including an increase in the size of the breasts due to milk production in preparation for childbirth. 

What some people may not know is that it is common for milk to actually leak at various stages of pregnancy before the baby is even born and begins breastfeeding. 

So, when does milk start leaking during pregnancy, and what’s important to know about it? 

Why Do Women Experience Leaking Milk During Pregnancy?

One of the most common symptoms of pregnancy is leaking breasts. As surprising and uncomfortable as this may be the first time you experience it, leaking milk is fairly normal and typically occurs as a result of an imbalance in pregnancy hormones.

Early in the first trimester, the body begins to release a hormone called prolactin.

This important hormone directs the body to begin the process of producing milk in preparation for childbirth, lactation, and breastfeeding. 

As the third trimester approaches and the levels of prolactin in the body increase, the breasts change and start to fill with colostrum, an early variation of breast milk that is filled with important nutrients.

Often off-white or light yellow in color, colostrum contains protein and antibodies that the baby needs during their first few days of life for protection against disease.

Also during this time, the placenta is producing estrogen and progesterone, which are supposed to prevent milk from leaking out of the breasts to ensure there is an adequate supply when the due date arrives. 

If these two hormones are imbalanced and there is an excess of prolactin, the breasts may begin to leak milk during pregnancy.

What Is Colostrum?

Colostrum is sometimes referred to as “liquid gold” because it is packed with protein and rich in antibodies that newborns need in order to thrive during their first days of life.

Colostrum typically comes in before mature breast milk in preparation for the birth of your baby, and is sometimes called “foremilk” or “first milk” as a result.

The mature milk supply starts to come in around three to four days after giving birth.

The substance provides the perfect nutrition for newborns and helps protect new babies against infection thanks to the antibodies that are transferred from mom to baby.

Colostrum varies in color; it may be a clear fluid, or it may be yellow, off-white, or even a little orange.

Compared to more mature breast milk, which is smoother in appearance and typically white or bluish-white in color, colostrum is typically thicker. 

Colostrum is easy on the baby’s digestive tract, as well, and has a laxative effect that helps clear a substance called meconium from the baby’s body.

Lingering meconium is known to contribute to jaundice, so it’s important that it’s cleared out quickly after the baby is born. 

Colostrum also contains healthy bacteria known as probiotics that are passed from mother to baby in order to help establish a healthy gut microbiome.

When Does Milk Production Begin During Pregnancy?

Many women begin producing colostrum about 14 weeks into pregnancy. However, a woman’s body is already gearing up to produce milk long before that. 

Among the earliest signs of pregnancy are increased size and tenderness of the breasts, as milk glands start to increase in size and grow in number shortly after conception.

The milk duct system is fully developed in the second trimester, which allows women to produce breast milk even if babies are born early.

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When Does Milk Start Leaking During Pregnancy?

A quick internet search will tell you that the approximate time frame in which breasts typically start leaking colostrum is around 14 weeks of pregnancy.

However, some women may experience leaking prior to this while others may never experience leaking at all. 

Most women are somewhere in the middle, experiencing a few drops of leakage only on occasion.

The breasts may leak milk on their own, or leaking may occur in response to stimulation of the nipples, such as during foreplay, exercise, or even when wearing an irritating bra or clothing.

Can You Prevent Milk Leaking During Pregnancy?

Unfortunately, it’s not possible to totally prevent milk from leaking during pregnancy. However, most women find that they are able to manage leaking by wearing breast pads or nursing pads inside the bra.

These work to absorb the small amounts of fluid that may leak out during the day and can prevent milk from soaking through to your clothes.

Is Leaking Milk During Pregnancy Dangerous?

For the most part, leaking milk during pregnancy is normal and completely safe.

However, there may be a few situations in which women should speak to their doctor. 

Breasts leaking more than a few drops of milk at a time, or leaking a thick or bloody substance, should be examined by a medical professional. 

While the symptoms are often normal and a sign of the milk ducts getting ready for childbirth and breastfeeding, they can also be a sign of a clogged milk duct, which can be painful.

Thankfully, clogged ducts can usually be easily treated in an OBGYN or other healthcare setting.

How Can I Minimize Milk Leaking During Pregnancy?

While there isn’t much that a woman can do to stop her breasts from leaking during pregnancy, the good news is that the amount of leaked colostrum is usually relatively little. 

Many people find that tucking nursing pads inside their bras and avoiding nipple stimulation when possible can helpl minimize the amount of colostrum that leaks.

It can also be helpful to avoid fabrics that rub the nipples or cause irritation, as this can stimulate milk production.

The Bottom Line

It is common for women to start leaking milk about 14 weeks into pregnancy; however, some women may experience leaking sooner, while others never leak at all. 

The tendency to leak milk during pregnancy is generally due to an imbalance of the hormones prolactin, which directs the body to begin the process of producing milk in preparation for childbirth and breastfeeding, and estrogen, which is supposed to help prevent milk from leaking out of the body in order to ensure there is an adequate supply when baby arrives. 

If a woman has more prolactin than estrogen, she may start leaking a substance called colostrum during pregnancy.

Leaking is rarely harmful, but if you have any concerns, schedule a wellness check-in with your OB-GYN for additional guidance. 

References and Sources:

Colostrum: What Is It, Benefits & What To Expect | Cleveland Clinic 

Prolactin: What It Is, Function & Symptoms | Cleveland Clinic 

Leaking from your nipples | NHS