Feeding your newborn baby – breastfeeding or formula feeding?

By (embryologist), (gynecologist), (embryologist) and (biochemist).
Last Update: 02/01/2024

One of the decisions a mother has to make after the birth of her child is how she is going to feed her baby. She may choose to breastfeed or bottle feed i.e. use formula.

Generally, exclusive breastfeeding is recommended by doctors and midwives during the first 6 months of the baby's life, and is also preferred by most mothers for the multitude of benefits it brings.

However, breastfeeding can have some drawbacks, so some women prefer to use artificial milks right from the start.


Breastfeeding is the process by which a woman feeds her newborn baby through her breasts, which begin to secrete milk immediately after delivery.

According to the World Health Organization (WHO), exclusive breastfeeding is the best way to provide the nutrients necessary for the proper development of the baby during the first six months of life.

Subsequently, it is possible to introduce other age-appropriate foods and/or alternate breastfeeding with formula feeding to meet nutritional needs as the baby grows. However, the WHO recommends continuing to breastfeed babies until age two.

Breastfeeding terminology

There are different types of breastfeeding depending on how it is done. In the following section we are going to to define the most commonly used terms:

Exclusive breastfeeding
the baby is exclusively breastfed, with no other liquid or solid supplements.
Predominant breastfeeding
breast milk is the main source of food, although the baby may receive other liquids such as water, infusions, juices, drops, or syrups.
Complementary feeding
the baby feeds on breast milk and other solid or liquid foods.
Direct Breastfeeding
when breastmilk is obtained directly by sucking on the breast, without the use of a breast pump or bottle.
Breastfeeding with expressed milk
in this case the breast milk is extracted from the mother's breast and given to the baby with the bottle.
Breastfeeding on demand
the baby starts to breastfeed whenever requested and for as long as necessary, without any type of schedule or number of established feedings.
Multiple Breastfeeding
when the mother breast-feeds two children of the same age after a multiple pregnancy.
Tandem Breastfeeding
when the mother breast-feeds two children of different ages.
Artificial or bottle feeding
when the baby doesn't feed on breast milk, but on formula.
Mixed Feeding
also known as complementary feeding, i.e. when the baby is fed both breast milk and formula.

In general, each woman chooses how to feed her baby, although it is advisable to consult with medical specialists or breastfeeding support groups.


Among the main advantages of breastfeeding the newborn, we highlight the following:

  • Prevents bacterial and viral infections by providing antibodies to the mother and helps develop the baby's immune system.
  • Facilitates digestion, bearing in mind that the newborn's digestive system is not yet fully functional.
  • It has a greater availability, since the milk is always ready and at the right temperature for the baby.
  • It creates a very strong emotional bond betweem mother and baby, which contributes to a better well-being and increased self-esteem.
  • It helps to burn calories in the mother's body and recover her body shape after childbirth.
  • Provides contraceptive protection for the mother by releasing prolactin, which prevents ovulation and therefore pregnancy.
  • Breast milk does not cost extra money, allowing parents to save and allocate resources to other needs.

Expressing milk using a breast pump

Some women indicate that breastfeeding is a kind of "slavery to your own children", as the woman must be available whenever the baby requires a feed, without the father being able to help or replace the mother at the time of feeding.

In fact, many women give up breastfeeding or combine it with formula feeding for this reason.

Today, however, it is possible to express milk using a breast pump, a device that allows the mother to express milk from her breasts, either manually or electrically, store it and give it to the baby with a bottle.

This type of breastfeeding allows someone else to feed the baby through the bottle. In addition, the mother can extract her milk and give it to the baby at another time, which offers greater freedom to do other activities.

However, the use of breast pumps also has some drawbacks:

  • The amount of milk obtained may be less due to the difficulty of expressing the milk. It can even cause discomfort or pain in some cases, especially when learning to use the pump.
  • The baby may later reject the breast.

In short, the use of a breast pump can be useful because it allows the baby to give the breast milk but via the bottle.

Formula feeding

Although breast milk is the perfect food for the newborn, it is not always possible.

There are occasions when breastfeeding does not allow the proper development of the baby and, therefore, many mothers are forced to stop breastfeeding their babies and move to formula feeding.

Some of the reasons that makev parents turn to formula feeding are the following:

  • Ineffective breastfeeding: milk production is not sufficient or there is an alteration in milk let-down.
  • The woman feels intense pain when breastfeeding.
  • The baby doesn't have enough force to suck, so it doesn't get the amount of milk it needs to grow properly.
  • The mother follows a medical treatment that forces her to take certain medications that are not compatible with breastfeeding, as they could reach the baby.
  • The mother has toxic and unhealthy habits, such as smoking or drinking alcohol, which can decrease not only the amount of milk produced but also its quality.
  • The mother has a disease or infection incompatible with breastfeeding, such as human immunodeficiency virus (HIV) or the appearance of herpes simplex on the nipple.
  • The baby suffers from galactosemia or phenylketonuria, pathologies that consist in the deficit of certain enzymes, which forces to take other types of special milks, without lactose and without phenylalanine, respectively.

It is also possible that formula feeding is resorted to by the mother's own choice, either for work or personal reasons. There are women who prefer to bottle-feed their baby directly, mainly because of the immense convenience involved.

Another of the reasons that women give for using formulas is that int his way the responsibility for feeding does not fall on them alone. Their partners or family members can help them in the feeding process. As such, they can better continue their daily routines.

Pregnancy and breastfeeding

While breastfeeding, the level of the hormone prolactin is higher than usual and this affects the hormones responsible for regulating the ovarian cycle. For this reason, ovulation and menstruation do not occur during breastfeeding.

However, the contraceptive protection of breastfeeding may not be effective. A small change in hormonal status can cause ovulation and thus pregnancy. Therefore, if a new pregnancy is not desired, it is recommended to use a barrier contraceptive method such as the condom.

Many women who have been mothers thanks to in vitro fertilization (IVF) ask if it is possible to transfer frozen embryos during lactation to have another baby as soon as possible, if they had embryos left over from the previous cycle.

Regarding this question, we have interviewed Dr. Gorka Barrenetxea, specialist in Gynecology and Obstetrics, who tells us:

Breastfeeding inhibits a woman's ovulation and therefore we should advocate exogenous administration of hormones at that time. What happens is that the administration of estrogens inhibits milk production and, therefore, it is very possible that the milk production of that woman decreases.

Because of these two circumtances , we recommend separating breastfeeding from the transfer of vitrified embryos.

FAQs from users

What is the three-month breastfeeding crisis?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

The three-month breastfeeding crisis occurs, when the baby is more restless during some days when being breastfed. This usually occurs at 3 months and is due to the baby's increased appetite, as he is growing and his body needs more food.

It is possible that the number of feedings is increased these days, but naturally the mother will produce more milk for the baby to be satisfied. It is not advisable to give the baby a bottle, even if the woman notices that her breasts are empty.

Until what age can I still breastfeed?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Currently, the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF) recommend continuing breastfeeding for at least two years. However, a mother can continue to breastfeed her baby until the age of 3 or 4.

How long can breast milk be stored in the fridge?

By Andrea Rodrigo B.Sc., M.Sc. (embryologist).

Breast milk can be stored in the refrigerator (0-4°C) for 5-8 days.

Should I switch to bottle feeding if my baby falls asleep during breastfeeding?

By Andrea Rodrigo B.Sc., M.Sc. (embryologist).

If the baby falls asleep breastfeeding and does not receive the amount of food necessary for proper growth and development, you should consult with the specialist the option of combining breastfeeding with artificial feeding or even the option of quitting breastfeeding and doing bottle feeding only.

Is smoking dangerous while breastfeeding?

By Andrea Rodrigo B.Sc., M.Sc. (embryologist).

Smoking during breastfeeding is generally not recommended. Numerous studies indicate that nicotine from tobacco passes into the mother's blood, although not in a concentration that may be toxic to the newborn.

In any case, the quality of the milk and the health of the baby will be better if the mother reduces or avoids harmful substances such as tobacco, alcohol and other drugs.

Can breastfeeding be used as a form of birth control?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

No. Although it is true that breastfeeding inhibits the menstrual cycle and usually prevents pregnancy, spontaneous ovulation and pregnancy can occur at any time.

Those women who decide to breastfeed should continue to take care of their diet, because as with pregnancy, the baby will receive nutrients through breast milk. You can read more about this in the following article:Feeding and nutrition for lactating mothers.

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Comité de Lactancia Materna de la Asociación Española de Pediatría. Recomendaciones sobre lactancia materna, 2012. (view)

Comité de Lactancia Materna de la Asociación Española de Pediatría. Preguntas frecuentes sobre lactancia materna, 2012. (view)

World Health Organization (WHO). Indicators for assessing infant and young child feeding practices. Conclusions of a consensus meeting held 6–8 November 2007 in Washington, DC, US. (view)

FAQs from users: 'What is the three-month breastfeeding crisis?', 'Until what age can I still breastfeed?', 'How long can breast milk be stored in the fridge?', 'Should I switch to bottle feeding if my baby falls asleep during breastfeeding?', 'Is smoking dangerous while breastfeeding?' and 'Can breastfeeding be used as a form of birth control?'.

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Authors and contributors

 Andrea Rodrigo
Andrea Rodrigo
B.Sc., M.Sc.
Bachelor's Degree in Biotechnology from the Polytechnic University of Valencia. Master's Degree in Biotechnology of Human Assisted Reproduction from the University of Valencia along with the Valencian Infertility Institute (IVI). Postgraduate course in Medical Genetics. More information about Andrea Rodrigo
 Gorka Barrenetxea Ziarrusta
Gorka Barrenetxea Ziarrusta
M.D., Ph.D.
Bachelor's Degree in Medicine & Surgery from the University of Navarra, with specialty in Obstetrics and Gynecology from the University of the Basque Country. He has over 30 years of experience in the field and works as a Titular Professor at the University of the Basque Country and the Master's Degree in Human Reproduction of the Complutense University of Madrid. Vice-president of the SEF. More information about Gorka Barrenetxea Ziarrusta
License: 484806591
 Zaira Salvador
Zaira Salvador
B.Sc., M.Sc.
Bachelor's Degree in Biotechnology from the Technical University of Valencia (UPV). Biotechnology Degree from the National University of Ireland en Galway (NUIG) and embryologist specializing in Assisted Reproduction, with a Master's Degree in Biotechnology of Human Reproduction from the University of Valencia (UV) and the Valencian Infertility Institute (IVI) More information about Zaira Salvador
License: 3185-CV
Adapted into english by:
 Michelle Lorraine Embleton
Michelle Lorraine Embleton
B.Sc. Ph.D.
PhD in Biochemistry, University of Bristol, UK, specialising in DNA : protein intereactions. BSc honours degree in Molecular Biology, Univerisity of Bristol. Translation and editing of scientific and medical literature.
More information about Michelle Lorraine Embleton

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