During a pregnancy, the influence of many different hormones cause the glands within the breasts to grow and change their structure.  The breasts can produce milk after about 5 or 6 months.

High levels of the prolactin hormone, combined with the sudden drop in progesterone caused by the birth, triggers the breasts to produce lots of milk.  This production is continuously stimulated by the suckling child who will both empty the breasts (thus promoting further production) and will stimulate oxytocin hormone production in the mother during feeding which has the effect of prompting further milk production within the mammary glands and allowing for a good flow from the nipple.

Just after the birth, the first milk that is produced is called 'colostrum'.  This is a watery looking substance that contains high levels of antibodies and is used to protect against infection and to gently prepare the baby's intestines for more substantial foods to come.  It also helps the baby evacuate the materials ingested whilst in the womb (meconium).  NOTE: Many but not all mothers will leak colostrum during the latter part of a pregnancy.  This is normal.

After about 4 days of feeding, the breasts start to create a certain level of mature milk, with the balance gradually changing towards fully mature milk over about 2 weeks.

Under what conditions can breastfeeding be a bad idea?

If the mother is carrying certain viruses (such as HIV) or if she needs to take certain strong medicines (like immune system suppressants) or if the mother is taking class A drugs (heroin, cocaine, amphetamines), then the risks of passing these on to the child will normally result in breastfeeding being recommended against. 

Women with a history of breast surgery can have problems with milk production after birth.

Also, if the child has galactosemia (an hereditary disease that makes lactose digestion impossible), then they should not be breastfed.

What is the mother's milk made up of?

• Mature maternal milk contains about 8 grams of carbohydrates (sugars) per 100ml.

• It contains a specific form of lactose that encourages the intestines to mature and grow it's own protective system.

• It contains protein in a form suited to the young baby's digestive system.

• It contains less calcium than other milk, but is fully digestible by the baby allowing for provision of the daily requirements.

• It contains fats that provide energy.

• It contains enzymes that babies need to break down foods, but cannot yet fully produce for themselves.

• It contains the mother's antibodies that help protect the baby.

Is the milk content the same during a feeding session?

No.  In fact, at the beginning of a feeding session, the milk is normally quite watery, then the emptier the breast becomes, the richer and denser the milk appears.  This is due to the content; the early milk is high in water and sugar content (which calms the thirst and hunger) and the later milk has higher levels of fat and protein, which is used between feeds by the baby for growth of body tissue.  

The fats are very important for the regulation of the baby's appetite, it is for this reason that it is recommended to allow the baby to suckle until he/she releases the breast before changing sides.

This page

    How do a woman's breasts produce milk?

    Under what conditions can breastfeeding be a bad idea?

    What is the mother's milk made up of?

    Is the milk content the same during a feeding session?

Page 2

    Is the milk stored in the breast?

    What are the advantages of maternal milk?

    How much milk is needed by the baby?

    What if there is too much or too little milk produced by the mother?