Breastfeeding During Pregnancy – Common Concerns About Safety

September 7th, 2011 by Dionna | 10 Comments
Posted in Breastfeeding/Lactivism, Compassionate Advocacy, Feed with Love and Respect, natural parenting, Pregnancy and Birth

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Pregnant mothers who continue to breastfeed often have questions about whether it is safe to nurse throughout pregnancy as well as what effects it will have on the health of their nurslings, their unborn babies, and themselves. I’ve been researching these questions myself, and I’d like to share some of the information I found with you. The bottom line is this: “There is no evidence that continued nursing would be harmful to” mother, fetus, or the current nursling.1

The information in this two-part series comes primarily from three incredible resources: Adventures in Tandem Nursing by Hilary Flower, Mothering Your Nursing Toddler by Norma Bumgarner, and I strongly recommend that pregnant mamas interested in nursing through pregnancy and/or tandem nursing read them.

Today I’ll look at four questions: Are there risks involved with breastfeeding during pregnancy? Are there risks to the mother’s health? Are there risks to the current nursling’s health? Are there risks to the fetus’s health?
In part two (“Common Concerns About Supply”), I’ll share information on three more questions: How many breastfeeding mothers will lose milk during pregnancy? How many nurslings will wean during pregnancy? What can I do to maintain my milk during pregnancy?

Click on each question to jump to the answer below:

Are there risks involved with breastfeeding during pregnancy?
Are there risks to the mother’s health?
Are there risks to the current nursling’s health?
Are there risks to the fetus’s health?


Are there risks involved with breastfeeding during pregnancy?

The main risk that breastfeeding mothers are warned against is the possibility of miscarriage or preterm labor. “Since breastfeeding stimulation has been shown to cause uterine contractions, many people wonder if breastfeeding could trigger problematic contractions during pregnancy.”2 Why does breastfeeding cause uterine contractions? When a nursling suckles, the body releases oxytocin, which is the chemical messenger necessary to stimulate let-down. “Through the release of oxytocin and prostaglandin breastfeeding also stimulates the uterus to contract.”3

What does research show? Well, so far, nothing. There have been no controlled studies on whether uterine contractions caused by breastfeeding can cause a mother to experience premature labor. But we do have “years of anecdotal experience with mothers who have been nursing through pregnancy, even those with a past history of miscarriage and premature delivery, and there is no readily apparent increase in either problem.”4 In one survey, only seven percent of women “recalled contractions related to breastfeeding at all.”5

There are at least two physical reasons that breastfeeding contractions are normally nothing to worry about. First, clinical observation has shown “that breastfeeding contractions do not produce dilation of the cervix.”6 Second, the uterus changes throughout pregnancy – during the majority of pregnancy (until about 38 weeks), nipple stimulation causes even “less oxytocin to be released compared with” women who are not pregnant. The uterus is simply not as responsive to oxytocin. After the uterus reaches “full term” around week 38, suddenly the uterus becomes more sensitive to oxytocin, and therefore nipple stimulation can more easily cause uterine contractions in women who are term.7 In other words, “[u]nless your pregnancy is term or the cervix is ripe, the released oxytocin stimulation is not sufficient to bring on labor.”8

Indeed, full-term women have successfully induced labor using nipple stimulation from a breast pump. But the amount of stimulation required is likely to be far more than any one nursling could sustain – the pumping necessary to induce labor ranges from 15 to 45 minutes of dedicated stimulation every hour for several hours. Even the most dedicated nursling would have trouble keeping up with that pace!9

Realistically, if you are able to have sex and orgasms (“both of which cause uterine contractions”), then breastfeeding will most likely not pose a risk for you either.10 And a final word on the risk of miscarriage or preterm labor from Lesley Regan, PhD, Md, who “heads the Miscarriage Clinic at St. Mary’s Hospital in London . . . . She [said]: ‘Once a pregnancy is clinically detectable, breastfeeding should pose no added risk of pregnancy loss. There isn’t any data suggesting a link between breastfeeding and miscarriage, and I see no plausible reasons for there to be a link.'”11


Are there risks to the mother’s health?

“Many mothers are warned that breastfeeding during pregnancy will deplete their body’s nutritional stores and harm their long-term health.” Research has shown, though, that well-nourished breastfeeding mothers do not need to be more concerned about their short or long-term health than other pregnant women. Maternal health risks are generally only experienced by malnourished mothers.12

Research has established that nursing pregnant mothers:

1) do not have an increased risk of bone loss/osteoporosis;

2) actually decrease their risk of breast cancer by increased breastfeeding (“breast cancer risk is reduced by 7 percent for each birth and an additional 4.3 percent for every 12 months of breastfeeding”); and

3) have little risk of losing fat reserves during breastfeeding, because our bodies are “designed to store up fat during pregnancy and then tap into these fat reserves for milk production in the early breastfeeding period.” Again, this is true more for healthy, well-nourished mothers, but even a malnourished mother can expect to recover her fat reserves if she nurses for 15 months or more.13


Are there risks to the current nursling’s health?

The concerns mothers usually have about the current nursling’s health are mainly about the quantity of breastmilk and the types of nutrients they are receiving from the breastmilk. Breastmilk quantity will vary from mother to mother (and from pregnancy to pregnancy for the same mother) and depends on your body’s chemistry (see the section below on “how many breastfeeding mothers will lose milk during pregnancy?”). You need be less concerned with the nutrients your nursling receives from your breastmilk: as long as your child is nursing, she will get nutritional and immunological benefits.

“It is true that a subsequent pregnancy can have a negative impact on the benefits of breastfeeding – but only in so far as it leads to premature weaning or diminished milk supplies.”14 For nurslings who still drink breastmilk as their primary source of nutrition, mothers should pay attention to the nursling’s weight gain and monitor their own breastmilk supply. “You may need to increasingly supplement with other foods and drinks [including donor breastmilk] if the amount of breastfeeding is shrinking for whatever reason.”15

Breastmilk – whether from pregnant or non-pregnant nursing mothers – really is nature’s super food. Breastmilk contains “growth factors, hormones, enzymes, and other substances that are immune-protective and foster proper growth and nutrition . . . .”16 “The milk of pregnant mothers continues to offer key immunological protection to young children[,]” as well as nutrients essential for growth.17 A study of random samples of milk from pregnant mothers found changes, lower levels of lipids and lactose and higher levels of protein, but nothing harmful. Another study tested the milk of three pregnant mothers over several months. About the second month of pregnancy the milk began to undergo changes similar to those observed during the course of weaning. Concentrations of sodium and protein gradually increased while milk volume, along with concentrations of glucose, lactose, and potassium, gradually fell. . . . Thus there is no reason to be concerned about ill effects in the nursing child.”18

Some mothers worry about the effects of pregnancy hormones on their nurslings. While some of these hormones “are present in the milk,” they are also present in breastfeeding mothers who take some oral contraceptives. “There seems little reason to worry, though, about natural hormones present at natural levels[; additionally, t]he developing fetus is exposed to the very same hormones at a much higher level [without ill effect].”19


Are there risks to the fetus’s health?

Please note that this section is largely on the fetus’s health only – it does not cover the health of your newborn if you decide to tandem nurse. That being said, there is plenty of evidence that shows “tandem nursing mothers produce ample milk.”20

“There are no obvious risks to the fetus in a healthy pregnancy.” As with any pregnancy, nursing mothers have healthier outcomes with good starting weights and healthy weight gain throughout the pregnancy.21 Mothers should listen to their own bodies’ needs so that they are ingesting enough to adequately sustain their own energy reserves, nourish the unborn child, maintain (as they are able) milk supply for the nursling, and to build up sufficient fat stores in . . . to support full lactation after the baby is born.”22

With respect to your toddler’s consumption of either breastmilk or colostrum during pregnancy, this will have no effect on “your new baby’s supply, since [the colostrum made before birth] is a ‘practice’ milk and is not being stored up for the baby’s use. Instead your body will make fresh colostrum for the newborn.”[Flower at 67.] Moreover, mothers who breastfed throughout pregnancy “appear to produce colostrum immediately postpartum, . . . although there may be some compositional differences. . . . If you are concerned about having enough to go around in the early days, you may be pleased to know that because you have breastfed before, colostrum will be more readily available after your new baby is born. [Additionally], milk yield increases rapidly after the first day, and particularly for mothers who have breastfed before.”23

What questions or concerns did you have about safely breastfeeding during pregnancy?
Be sure to stay tuned for part two, “Common Concerns About Supply.”


Statements on this website have not been evaluated by the Food and Drug Administration. Products and/or information are not intended to diagnose, cure, treat, or prevent any disease. Readers are advised to do their own research and make decisions in partnership with your health care provider. If you are pregnant, nursing, have a medical condition or are taking any medication, please consult your physician. Nothing you read here should be relied upon to determine dietary changes, a medical diagnosis or courses of treatment.

  1. Mothering Your Nursing Toddler by Norma Bumgarner at 121.
  2. Adventures in Tandem Nursing by Hilary Flower at 223.
  3. Flower at 225.
  4. Bumgarner at 130.
  5. Flower at 225.
  6. Flower at 225.
  7. Flower at 226-27 (emphasis added).
  8. Can I Breastfeed During Pregnancy?
  9. Bumgarner at 130-31, Flower at 226-27.
  10. Bumgarner at 131.
  11. Flower at 228.
  12. Flower at 211.
  13. Flower at 211, 213-14.
  14. Flower at 215.
  15. Flower at 256.
  16. Hamosh, Margit, PhD, Breastfeeding: Unraveling the Mysteries of Mother’s Milk.
  17. Flower at 215.
  18. Bumgarner at 122-23; see also Flower at 61.
  19. Bumgarner at 132; see also Flower at 61.
  20. Flower at 233.
  21. Flower at 220-21.
  22. Bumgarner at 131.
  23. Flower at 69-70.

10 Responses to:
"Breastfeeding During Pregnancy – Common Concerns About Safety"

  1. Good to see articles like this! I was searching high and low for articles like this when I was considering on continuing breastfeeding during my breastfeeding and thank God, alot of supportive mums on Facebook recommended the “Adventures in Tandem Nursing” book which I bought and read each and every word.

    Needless to say, I continue BFing during my pregnancy and is now on my 5th day on tandem nursing :)

    Btw, Lauren, my baby girl is born naturally on 2nd Sept. Wish you all the best with yours! :)

  2. Rachael   RachaelNevins

    Aha. My only concern had been about preterm labor (though not too, too concerned — I figured if there were really something to worry about, I’d have heard about it at LLL). This explanation makes sense!

  3. Serena

    Excellent article. I am currently breastfeeding my one year old at 28 weeks pregnant. The only problem we’ve encountered is the decrease in my milk supply. I am planning to tandem nurse once the new baby gets here.

    • Dionna   CodeNameMama

      We’ve had the same problem Serena – I lost my milk supply at 10 wks, but Kieran was quite pleased when the colostrum came back in at 27 wks!

  4. Well,it is always advisable to keep 3 years gap between two children, as mother’s body need to make up all again for the second baby.
    Anyways,in this case mother need to be extra cautious and take healthy food and the pre vitamins as she need to feed two babies and also take care of herself.

  5. Good Girl Gone Green   GGirlGGreen

    Thanks for all the wonderful information, Dionna! :)

  6. Charise@I Thought I Knew Mama   ithoughtiknewma

    Thank you for this very informative post! I imagine at some point down the road, I will be pregnant again and since I know Baby would probably enjoy nursing forever :-), I’ve had some questions about how nursing would be for all involved.

    Also, thanks for linking up at Green & Natural Mamas Thursday!

  7. Heather

    GREAT read!

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