Can You Get Pregnant While Breastfeeding? Understanding Your Fertility During Lactation

The relationship between breastfeeding and fertility is fascinating and complex, often leaving many new mothers with questions. Breastfeeding can naturally delay the return of fertility, but it is important to understand the science behind menstrual cycles, ovulation, and how lactation impacts reproductive hormones. Please note that every person’s body is different, and this blog is not a substitute for medical advice tailored to an individual’s health journey.

Breastfeeding affects fertility primarily through the influence of the hormone prolactin . Prolactin is responsible for stimulating milk production and also has a suppressive effect on the reproductive system. Elevated prolactin levels during breastfeeding inhibit the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus, which in turn reduces the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) . These hormones are essential for ovulation, so their suppression can delay the return of fertility.

(1)This process is known as lactational amenorrhea , or the temporary absence of menstruation due to breastfeeding. For many women, lactational amenorrhea acts as a natural contraceptive, as ovulation remains suppressed while prolactin levels are high. However, this effect is not permanent and depends on breastfeeding patterns and other factors.(2)

This phenomenon is known as lactational amenorrhea , or the temporary absence of menstruation due to breastfeeding. For many women, lactational amenorrhea can act as a natural contraceptive, as ovulation is suppressed when prolactin levels remain high (3). However, this effect is not permanent and depends on breastfeeding patterns and other factors.

The Lactational Amenorrhea Method (LAM) is a natural form of birth control that relies on the fertility-suppressing effects of breastfeeding. When used correctly, LAM can be up to 98% effective (4).

The Three Essential Criteria for LAM Effectiveness:

1. Exclusive Breastfeeding: The baby must receive breast milk as their sole source of nutrition, without supplementation with formula, water, or solid foods.

2. Baby is Less Than 6 Months Old: LAM is most effective during the first six months postpartum, when prolactin levels are highest.

3. No Return of Menstrual Periods: The absence of menstrual bleeding suggests that ovulation has not resumed.

If any of these criteria are no longer met, the effectiveness of LAM decreases significantly, and alternative contraceptive methods should be considered.

If any of these criteria are no longer met, the effectiveness of LAM decreases significantly, and alternative contraceptive methods should be considered (5).

Although lactational amenorrhea can provide temporary birth control, it is not a guaranteed method for preventing pregnancy. Ovulation  always  occurs before the first postpartum period, meaning that a woman could conceive without realizing her fertility has returned. Most people ovulate 10-17 days before their period, but this can vary from person to person.

Factors That Reduce the Effectiveness of LAM

Several factors can lead to a decrease in prolactin levels and the resumption of ovulation:

• Supplementing with Formula: Reduces the frequency of breastfeeding, lowering prolactin levels.

• Introducing Solid Foods: Babies who begin eating solids breastfeed less often, which can reduce lactational amenorrhea’s effectiveness.

• Baby Sleeping Through the Night: Longer stretches between feedings decrease the hormonal signals needed to suppress ovulation.

Reduced Nursing Frequency: Returning to work or other life changes that limit breastfeeding sessions can hasten the return of fertility. (6)

For breastfeeding moms, recognizing the signs of returning fertility (7) can help with family planning and understanding when additional contraceptive methods may be necessary. Key signs include:

• Changes in Cervical Mucus: Fertile cervical mucus becomes clear, stretchy, and egg-white-like.

• Return of Menstrual Cycles: Light spotting or breakthrough bleeding may symbolize the rise of FSH and LH signaling that the body is returning to ovulate.  You may have spotting prior to a period without ovulation, but for a bleed to be considered a true period, there must be confirmed ovulation.  

• Changes in Breastfeeding Patterns: Reduced feeding frequency or baby’s increased interest in solids may indicate hormonal shifts.

• Physical Symptoms of Ovulation: Some women experience mild abdominal pain (mittelschmerz), breast tenderness, or increased libido around ovulation.

If you notice any of these signs, it’s a good idea to discuss contraceptive options with your healthcare provider if you wish to avoid pregnancy.

When you’re ready to expand your family, understanding the timing of fertility’s return is crucial. Proper planning can help optimize both maternal and fetal health.

Optimal Spacing Between Pregnancies

The World Health Organization (WHO) recommends waiting at least 18-24 months after childbirth before conceiving again.(8,9) This spacing allows the mother’s body to fully recover, reduces the risk of complications, and helps promote healthier outcomes for both mom and baby.

Impact on Milk Supply During Pregnancy

Becoming pregnant while breastfeeding can lead to changes in milk supply and composition due to hormonal shifts. Some moms find it challenging to continue breastfeeding during pregnancy, while others choose to wean gradually.

Nutritional Considerations

If you plan to breastfeed while pregnant or conceive soon after giving birth, prioritize a nutrient-rich diet. Key nutrients include:

• Calcium and Vitamin D for bone health.

• Calcium and Magnesium supplementation after ovulation can help avoid a decrease in milk supply during menstruation. 

• Iron to support red blood cells.

• Folate to support fetal development and reduce the risk of neural tube defects.

• Choline to support fetal brain development. 

Continuing with a high-quality prenatal vitamin during breastfeeding and while trying to conceive is essential to replenish nutrients lost during pregnancy and lactation. Legendairy Milk's Dynamic Duo® Prenatal & Postnatal vitamins are specifically formulated to support mothers during these critical periods. The AM formula includes iron, vitamins B6 and B12, choline, and biotin, while the PM formula provides calcium, magnesium, vitamin D3, vitamin K2, and additional choline. This separation ensures optimal absorption and utilization of these vital nutrients..(10)

If you’re not ready for another pregnancy, choosing a safe and effective contraceptive method is essential. Some options are specifically designed to be compatible with lactation.

Safe Contraceptive Methods During Lactation (11)

1. Progestin-Only Pills (Mini-Pill):

   • Safe for breastfeeding mothers as they do not affect milk supply.

2. Intrauterine Devices (IUDs):

   • Both hormonal and non-hormonal (copper) IUDs are safe and highly effective options.

3. Barrier Methods:

   • Condoms and diaphragms provide non-hormonal birth control options.

4. Natural Family Planning (NFP):

   • Monitoring fertility signs like cervical mucus and basal body temperature can be effective with proper training and consistency.

Timing Considerations

• Some contraceptives, like IUDs, can be inserted immediately postpartum, while others may require waiting a few weeks to ensure optimal effectiveness and safety.

Discussing Options with Your Healthcare Provider

Each woman’s needs and preferences are unique. Be sure to discuss your goals and breastfeeding plans with your healthcare provider to select the best method for you.

Understanding your fertility during breastfeeding can help you make informed decisions about family planning and contraception. While breastfeeding can suppress ovulation and provide natural birth control through the Lactational Amenorrhea Method, its effectiveness is limited to specific conditions. Recognizing the signs of returning fertility and knowing when to consider additional contraceptive methods are key to avoiding unintended pregnancies.

Whether you’re planning for another baby or looking to delay your next pregnancy, safe and effective options are available. By staying informed and consulting with your healthcare provider, you can navigate this unique phase of life with confidence. Understanding how breastfeeding intersects with your fertility empowers you to make the best choices for yourself and your family.

1. https://www.reproductivefacts.org/news-and-publications/fact-sheets-and-infographics/hyperprolactinemia-high-prolactin-levels/ 
2. https://pubmed.ncbi.nlm.nih.gov/387162/ 
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC1595106/ 
4. https://pmc.ncbi.nlm.nih.gov/articles/PMC1595106/ 
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC1595106/ 
6. https://pubmed.ncbi.nlm.nih.gov/9678098/ 
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC6322125/ 
8. https://kellymom.com/tandem-faq/16milkchanges/ 
9. https://www.who.int/publications/i/item/WHO-RHR-07.1 
10. https://www.legendairymilk.com/blogs/legendairy-tips/why-does-legendairy-milks-prenatal-vitamin-have-separate-ampm-doses?srsltid=AfmBOopKE78ZRewMf237y-QLBNHEit8S-aYOl5bVOcuh58oD5a95EW9r&
11. https://www.plannedparenthood.org/learn/birth-control/breastfeeding/whats-best-birth-control-option-while-breastfeeding