Breastfeeding and Fertility

Breastfeeding is mother nature’s birth spacing, our body’s way of suppressing fertility while we have an avidly breastfeeding child. ;Breastfeeding still contributes more to birth spacing worldwide than all other family planning options combined. Even so, the common belief that “you can’t get pregnant while breastfeeding,” is quite untrue. ;Indeed, in one study of breastfeeding mothers in the US, 61% overlapped breastfeeding and pregnancy.1 ;The key is that most women’s bodies have a threshold of suckling below which breastfeeding and fertility are perfectly compatible. ;

While I was researching my book on breastfeeding during pregnancy (Adventures in Tandem Nursing: Breastfeeding during Pregnancy and Beyond, published by La Leche League International in July 2003) I was intrigued by my contributors’ stories about how they came to be pregnant while breastfeeding. ;I also found myself fielding questions from mothers who wished to hasten or delay such an event. ;Breastfeeding and fertility are so intricately intertwined that it can be a bit tricky to disentangle them, and the many myths and out-dated pieces of information out there don’t make it any easier. ;To get to the bottom of it I read up on the latest research. ;Here’s what I learned.

How does breastfeeding cause infertility?
Well, as you may remember, eggs need to ripen in mature follicles. ;In the early weeks and months after a baby is born, the baby’s intense suckling stimulation disrupts the hormonal coordination that stimulates follicle growth. ;This suspension of menstrual cycling is known as lactational amenorrhea. ;The hormone prolactin, so important for milk production, was originally thought to control breastfeeding infertility as well. ;Recent research has been unable to identify the precise hormonal pathway through which suckling manages to disrupt the reproductive hormones, but at this time there is no obvious role for prolactin.2

Fertility returns
The departure from lactational infertility is a story unto itself. ;Fertility can return abruptly or gradually, depending in large part on whether the change in breastfeeding is itself abrupt or gradual. ;The more rapid the reduction in nursing, the more likely the first postpartum menstrual cycle will be normally fertile.2

What does the gradual return of fertility look like? ;Researchers have used ultrasound to answer this question, comparing the visible signs with the mothers’ breastfeeding pattern. ;The first sign is limited follicle growth for one or more cycles. ;Eventually, the suckling stimulus abates enough to allow follicle growth that is apparently normal. ;Now an egg has a mature follicle in which to ripen; will an egg fully ripen and be released? ;For one or more cycles ovulation may not quite occur, the ovaries “try” to ovulate and then the follicles recede again. These are known as “anovulatory cycles.” ;Once ovulation is achieved the final question is: Has the uterus been prepared in advance for implantation? ;In some cases suckling caused delays in getting follicle growth going, with a longer time to ovulation and then a short post-ovulatory phase (known as the luteal phase), leaving the uterus inadequately prepared for implantation. ;A further reduction in breastfeeding generally results in a return to a normal luteal phase and the possibility of successful implantation.3

The first postpartum menstrual bleed generally occurs before the first successful ovulation, earning it the title “warning menses.” ;Menstruation is triggered by the sudden drop in estrogen that occurs when follicles stop growing and die. ;In a cycle where the follicles grow but do not reach maturity, menstrual cycles may be anovulatory. ;It is also possible to have ovulatory menstrual cycles that are incapable of sustaining a pregnancy due to inadequate functioning of the corpus luteum, as discussed above.

If you are curious about the state of your fertility, you can discern it quite accurately with fertility awareness methods, by charting the pattern of such signs as your basal body temperature, cervical mucus (consistency and amount), cervical height and softness, and cervical opening (which can be examined with a mirror). ;During amenorrhea you may see weeks of wet cervical fluid while your body attempts to ovulate and then repeats the cycle. ;Observation of your cervix can be clarifying during cycles of possible anovulation. ;Toni Weschler’s Taking Charge of Your Fertility is an wonderful guide for novice charters and she has a section devoted to breastfeeding mothers.

By the time you are experiencing regular cycles it is unlikely that breastfeeding is affecting your the chances of pregnancy. ;(Indeed, some mums are fertile while their cycles are still short, long, or irregular.) ;And after all this talk about incomplete fertility, it is important to be clear that once implantation occurs and the pregnancy can be clinically detected, there is no reason to believe that breastfeeding can affect the progress of a pregnancy. 4

Lactational amenorrhea as birth control: LAM
When the early months of lactational amenorrhea are intentionally used as birth control method (The Lactational Amenorrhea Method, or LAM) it is very effective: 99.3%.5 ;LAM requires that all three of the following conditions be met: (1) you are in the first six months after your baby was born, (2) your period has not returned, and (3) you are fully or nearly fully breastfeeding. Night-weaning can be compatible with continued lactational amenorrhoea; the trick is that overall suckling duration in 24 hours must remain high.6 ;

Pumping does not have quite the same effect as breastfeeding on reproductive hormones. ;One study found a pregnancy rate of 5.2% within the first six months of LAM for mothers returning to work less than four months postpartum and pumped milk for their babies. 7 ;Indeed I heard from one working mother who returned to work at four months became pregnant without a period at six months, while thinking she was still protected by LAM. The more frequently you pump and the less time you are away from your baby, the greater the chance that lactational amenorrhea will remain in effect.

You have an increased chance of pregnancy before your first period in the later months, a 4-7% chance at twelve months and a 13% at twenty-four months.8 9 ;Fortunately there are clues. ;In one study of twelve breastfeeding mothers, two of whom became pregnant before the first menses (one at six months postpartum and one after one year). ;Both had experienced a “sharp decrease” in both suckling frequency and duration of feeds in the week or two before ovulation.3 When illness, separations, or other circumstances create a rapid drop in breastfeeding, it pays to use back-up or abstinence if you are intent on avoiding pregnancy. ;

Lactational amenorrhea commonly lasts one or two years for mothers breastfeeding on demand. What makes the difference? ;Nutrition has only a minor effect on lactational amenorrhea and only in cases of malnourishment. Your natural hormone levels exert some influence as well. ;By far the biggest factor is your breastfeeding pattern, according to a study by the World Health Organization, based on data from 4,118 women in seven countries. ;This study found that the most important factor of all was the total duration of breastfeeding over a 24 hr period.6 ;The keys to extending lactational infertility are keeping frequency and duration of breastfeeding high, adding supplementary feeds gradually, and only after a breastfeeding session. Because you will have a distinctive breastfeeding pattern with each child, you may encounter differences after each birth.

I nursed my first daughter "round the clock," and I didn't have a period for almost 2-1/2 years after her birth. ;This fit right in to our plans to have children 3-1/2 to 4 years apart. ;Although my nursing style didn't change the second time around, my period started about 8 months after my son's birth, so trying not to get pregnant for a couple more years became the challenge. ;–>Veronica, California

Another question that often arises is: Can you go back into lactational amenorrhea once you’ve left? ;Yes. ;The classic case is when a temporary barrier to the baby’s nursing is removed, for instance a baby becomes ill and then recovers, or a mother is hospitalized and then returns home. ;One mother told me she started missing periods after starting to breastfeed a foster baby alongside her toddler. ;Interestingly, simply encouraging a baby to nurse more is not enough. ;In one study in Chile, although mothers succeeded in enticing their babies to increase suckling frequency, the overall duration remained low, and cycling continued.10

Birth control after LAM
During the first six months of LAM, back up birth control is unnecessary. ;As lactational amenorrhoea goes past six months - or if menstruation has resumed - you may well be in the market for a birth control method that is compatible with breastfeeding. ;Non-hormonal methods are ideal; they are just as effective while breastfeeding, and none of them affect the breastmilk.11

But breastfeeding itself is fully compatible with IUD use, indeed breastfeeding moms have fewer removals due to pain or bleeding.There’s just one thing to know. ;One mother wrote to me: ;“When my second pregnancy was confirmed we discovered that the IUD had been unattached the whole time!” ;The key to minimizing the risk of IUD expulsion is to have an experienced practitioner insert it within 10 minutes of delivery of the placenta. 12

If you are using Natural Family Planning during breastfeeding, include observations of your breastfeeding pattern on your chart. ;When breastfeeding changes are afoot, or if you observe a change in your basic infertile pattern, you will do well to abstain from intercourse until the situation is clear. ;A study of breastfeeding mothers using the fertility awareness method found it to be highly effective, and recommended an added precaution of abstaining from intercourse during the pre-ovulatory phase of the first three cycles.13

And do remember that some babies leap at narrow opportunities. ;Take notice of the effectiveness of your method and any sources of user error. ;Natural Family Planning is 99% effective when used accurately and consistently.14 IUDs are 95% to 98% effective, cervical caps and diaphragms are 85% to 88% effective, condoms are 80% to 85% effective, and vaginal suppositories, jellies, or creams are only 80% effective. 11
My husband and I certainly hadn't planned on becoming pregnant again so quickly. ;My 10 month old son still nursed roughly 8 times a day including nursing on and off most of the night. ;I had had a few erratic menstrual cycles starting at 6 months, so we were also using condoms - but we still became pregnant. ;My husband was the one who told me I was pregnant, since apparently I’m a bit more moody during pregnancy. ;A few weeks later a test confirmed this. ;We were very surprised, though we soon came to be thrilled over this miracle in our lives. - Tiffany, Oklahoma

Finally, let’s look at hormonal methods. ;They, too, are just as effective while breastfeeding, but their impact on breastfeeding is a significant concern. 13 ;Anecdotal reports of dwindling supply are still common, particularly for estrogen-containing products (including “combination” pills), but also occasionally for progestin-only products. ;A six-year follow-up study published in 2002 found that orally active progestin products (like Norplant) can increase the incidence of mild respiratory infections, skin conditions, and eye infections. 15

To use hormonal birth control while breastfeeding, use caution:

wait a minimum of six weeks postpartum so that your supply is established

;

favor progestin-only pills

;

seek orally inactive versions when possible

;

take the lowest dose you can

;

take the pill as far as you can from the next feeding time (as you would with any medication)

;

closely monitor your supply (sometimes the drop in supply is gradual)

;

discontinue use if your supply is negatively affected

;

if you are interested in injections, you may consider experimenting first with a pill to evaluate the effects on milk production.

;

;

Trying to conceive while breastfeeding
Pregnancy, breastfeeding, and a new pregnancy - with little or no menstruation in between--is the norm for our species. ;Some moms warm up to the advantages.
I wanted another child, we wanted another one! But my menstruation did not come after Alice’s birth, not yet, and she was about 18 months! I was so sad....then I stopped worrying about it and the menstruation came back and I became pregnant immediately. ;In five years I had just one menstruation...it has been wonderful! ;--Anna, Italy

Charting your fertility can be a powerful tool for mothers who are eager to welcome a new baby into the family. ;It is even possible to catch the first postpartum egg, with patience, knowledge and a bit of luck. ;
When my daughter was approaching two years of age, we wanted to conceive, but I still hadn’t had my first period. ;Checking cervical mucus during lactational amenorrhoea was frustrating because each month it appeared that I was about to ovulate, so I would get my hopes up. ;I was just learning to chart my cycles using a book, so I thought I might not have been doing it quite right. ;Still, I checked periodically out of curiosity, and when I did get pregnant, I had actually noted to my husband that it was the stretchiest cervical mucus I had seen yet. - Jacqueline, California

If you are experiencing amenorrhea or irregular periods while breastfeeding you may consider experimenting with reductions in breastfeeding frequency or duration. ;You may be glad to note that weaning is rarely necessary for the return of fertility, but there is no magic or typical threshold of breastfeeding intensity that predicts the return of fertility. ;Research does suggest that abrupt changes bring back fertility more rapidly and at a higher threshold of breastfeeding frequency than gradual changes. 3 ;

Sometimes, taking your nursling’s lead is the best policy. ;Mother Nature has her reasons for suspending your fertility while your child’s breastfeeding is intense, after all. ;Pregnancy and breastfeeding can safely overlap, but pregnancy does have a knack for causing weaning, especially if your milk diminishes or if it becomes painful for you, so it is ideal to wait until your child’s need to nurse is already waning.
Both times when I had a toddler nursing it was difficult for me to become pregnant. ;We use Fertility Awareness Method (FAM) so I could tell exactly what was going on with my cycles. ;I was ovulating and menstruating, but my luteal phase wasn't long enough. ;We just had to be patient, in the long run. ;Once each child stopped nursing during the night, that's when my luteal phases became long enough. ;I was a little vexed at being thwarted at trying to get pregnant for many months, but my husband just laughed and assured me we'd have a large family some day. ;When I think about it now, it's obvious my body just kept saying, "I'd better not let you have another baby until this one grows up." ;--Pamela, Washington State

If you had fertility problems in the past, you are probably wondering if the old problems are still there. ;You may want to use back-up birth control unless you are ready for a miracle baby. ;I heard many tandem nursing stories that began like this mother’s:
I believe the exact words out of my mouth were “I don’t need contraception – I’m scorchingly infertile!” ;I had had a year of fertility treatment to fall pregnant with my first son, so I assumed I would need fertility treatment to fall pregnant a second time.
About 9 months after my first son was born I wanted to drink a glass of champagne, and so I took a pregnancy test just incase. ;Needless to say I didn’t get to drink it! ;--Kirsten, Australia

Still, overall, mothers who needed fertility assistance the first time around are likely to need help again. ;If you’re eager to become pregnant, first steps may include charting some cycles (ideally to be compared with your cycles before you were breastfeeding), or reducing breastfeeding to evaluate your fertility status. ;

If you are considering assisted reproductive technologies, you will want to consider whether the treatment will affect breastfeeding and vice versa. ;You can obtain research-based information about how drugs affect milk in Thomas Hale, PhD’s reference manual Medications and Mothers’ Milk. Many drugs have never been tested for safety while breastfeeding, and carry a cautionary label just in case. As always, consult your caregiver about taking any drugs while breastfeeding. ;When ;I wrote him about this, Hale offered this opinion:
Most of the fertility drugs are not believed to pass into milk in clinically relevant amounts because their molecular weights are simply too high to permit entry. ;In addition they are not likely to be orally bio-available to the infant even if present in the milk because they are large peptides and proteins.

Hale’s clinical observations suggest that Clomiphene (trade name Clomid) is compatible with breastfeeding after lactation is established, and he notes that this makes sense given how Clomid affects the hormonal system.

On the other side of the issue, might continued breastfeeding negatively affect the success of your fertility treatment? ;Hormonal treatments to promote ovulation and in vitro fertilization should not be affected by breastfeeding at all, according to Alan McNeilly, PhD. ;McNeilly’s research on the return of fertility while breastfeeding has been at the leading edge for the last twenty years; he is Professor and Deputy Director of the Medical Research Council’s Human Reproductive Sciences Unit in Edinburgh Scotland. ;McNeilly notes that the hormonal treatments take over control of the ovarian cycle, and breastfeeding should not influence fertility under those circumstances. ;

By contrast, donor insemination or insemination with your partner’s sperm may be more challenging while breastfeeding. ;If you have no control over your menstrual cycle, then menstrual irregularities could interfere both with the timing of insemination as well as the post-ovulatory phase and implantation. ;I heard from one mother in New Zealand who flew out to a distant city for her scheduled insemination, only to end up staying in a hotel for a couple days because breastfeeding delayed her ovulation. (She is now tandem nursing, nursing her toddler and newborn together.) ;Ideally, insemination should take place in a properly monitored cycle in order to be sure the sperm and egg are in the same place at the same time. ;You can monitor your cycle at home using fertility awareness charts or dipstick LH Assay kits from your pharmacy.

Participating in the mystery
As you can see, fertility while breastfeeding can be managed to a great degree. ;You can return to your normal fertility while breastfeeding, or keep fertility in check without compromising the safety of continued nursing. ;Of course, some babies have plans of their own, coming sooner or later than their parents planned - and sometimes their nursing siblings delay their arrival a bit! ;In the end, the initiation of new life is often a mystery. ;Trust your nursling, your body and mind, and any would-be babies up there in the ethers to work together for the best outcome for the whole family.

Hilary Dervin Flower, MA, lives in Florida with her partner Ben, and her children Miles (2) and ;Nora Jade (5). ;She tandem nursed for 18 months. Adventures in Tandem Nursing: Breastfeeding during Pregnancy and Beyond is her first book, with a forward by Peggy O’Mara, published by La Leche League International in July 2003. ;She is avidly collecting mothers’ insights for a new gentle discipline book she is writing for La Leche League International. ;She invites you to visit her at www.nursingtwo.com.

Acknowledgements: I wish to gratefully acknowledge the generous assistance of Alan McNeilly in answering my many questions and reviewing early versions of this manuscript, and the vital help of many mothers’ sharing their stories and questions with me.

References cited:

1 Unpublished data, Kathleen Kendall-Tackett, Ph.D., IBCLC, Sugarman, M., M.D., 2003, appearing in Flower, Hilary Adventures in Tandem Nursing: Breastfeeding during Pregnancy and Beyond, La Leche League International, Schaumburg, IL, July 2003, page 16.

2 McNeilly, AS. ;Neuroendocrine changes in fertility in breast-feeding women. Chapter14. ;In. J.A. Russell et al. (Eds) Progress in Brain Research, Vol 133. ;2001 Elsevier Science B.V. P.207-214.

3 McNeilly, AS, Glasier, AF, Howie PW, Houston MJ, Cook A, Boyle H. Fertility after childbirth: Pregnancy associated with breastfeeding. Clinical Endocrinology (1983) 18:167-173.

4 The comments of Alan McNeilly, PhD, and Lesley Regan, PhD, MD., 2003, appearing in Flower, Hilary Adventures in Tandem Nursing: Breastfeeding during Pregnancy and Beyond, La Leche League International, Schaumburg, IL, July 2003, page 224.

5 Kennedy KI, Visness CM. Contraceptive efficacy of lactational amenorrhoea. Lancet 1992 Jan 25;339(8787):227-30

6 [no author specified] World Health Organization Task Force on Methods for the Natural Regulation of Fertility. The World Health Organization Multinational Study of Breast-feeding and Lactational Amenorrhea. II. Factors associated with the length of amenorrhea. Fertil Steril 1998 Sep;70(3):461-71

7 Valdes V, Labbok MH, Pugin E, Perez A. ;The efficacy of the lactational amenorrhea method (LAM) among working women. Contraception 2000 Nov;62(5):217-9

8 The World Health Organization multinational study of breast-feeding and lactational amenorrhea. III. Pregnancy during breast-feeding. World Health Organization Task Force on Methods for the Natural Regulation of Fertility. Fertil Steril 1999 Sep;72(3):431-40

9 Short, R., Lewis, P., Renfree, M., et al. ;Contraceptive effects of extended lactational amenorrhoea. ;Beyond the Belagio Consensus. ;Lancet 1991; 337: 715-717.

10 Diaz S, Miranda P, Brandeis A, Cardenas H, Croxatto HB. A study on the feasibility of suppressing ovarian activity following the end of postpartum amenorrhoea by increasing the frequency of suckling. Clin Endocrinol (Oxf) 1988 May;28(5):525-35

11 Lawrence, R. Breastfeeding: A Guide For The Medical Profession. ;St. Louis: Mosby, 1999; 666.

12 Kennedy KI. Post-partum contraception. Baillieres Clin Obstet Gynaecol 1996 Apr;10(1):25-41

13 Kennedy, KI., Gross, BA., Parenteau-Carreau, S., Flynn, AM., Brown, JB., Visness, CM. Breastfeeding and the Symptothermal Method. Studies in Family Planning (1995) 26(2):107-115.

14 Geerling JH. Natural family planning. Am Fam Physician 1995 Nov 1;52(6):1749-56, 1759-60.

15 Schiappacasse V, Diaz S, Zepeda A, Alvarado R, Herreros C. Health and growth of infants breastfed by Norplant contraceptive implants users: a six-year follow-up study. Contraception 2002 Jul;66(1):57-65

;