For Premature Babies Born by C-Section, Umbilical Cord Milking Is a Good Option

It’s well-established that infants born prematurely benefit from a delay in umbilical cord clamping. However, many preemies are born by cesarean section, and delayed cord clamping may be less effective and practical after surgical birth. Some obstetricians opt to speed things up by “milking” the umbilical cord, manually pushing blood from the placenta to the baby. A study published in Pediatrics this week shows that cord milking can be just as effective – if not more so – than waiting to cut the cord in premature babies born by C-section [full text PDF].1

No, this baby doesn't look like a preemie! U.S. Navy Medical Officer Cmdr. Michael Cackovic prepares to cut the cord during a cesarean section on an Honduran patient during Southern Partnership Station 2014 (SPS-JHSV 14). (U.S. Navy photo by Mass Communication Specialist 1st Class Rafael Martie, Public Domain)

No, this baby doesn’t look like a preemie! U.S. Navy Medical Officer Cmdr. Michael Cackovic prepares to cut the cord during a cesarean section on an Honduran patient during Southern Partnership Station 2014 (SPS-JHSV 14). (U.S. Navy photo by Mass Communication Specialist 1st Class Rafael Martie, Public Domain)

In premature infants, delaying cord clamping for at least 30 seconds is associated with lower risk of intraventricular hemorrhage (IVH, bleeding in the brain), necrotizing enterocolitis (death of intestinal tissue), and anemia.2 Delayed cord clamping also benefits full-term babies, though the outcomes are less dramatic.3

Since 2012, ACOG has recommended a 30-60 second delay in umbilical cord clamping for preterm infants.4 However, they noted that little was known about the efficacy of delayed cord clamping after a C-section or about umbilical cord milking:

“More studies are needed to evaluate the potential benefits and risks of umbilical cord milking, and at this time there is insufficient evidence to support umbilical cord milking in preterm infants.”

“The ideal time for clamping the umbilical cord after cesarean delivery versus vaginal birth is an especially important area for future research. Premature infants, who may benefit most from delayed umbilical cord clamping, are more likely to be delivered by cesarean delivery because their mothers may have other medical and obstetric complications.”

These gaps in the research are definitely a challenge to implementing delayed cord clamping in premature infants. After a C-section, holding a wet, squirmy baby to delay cord clamping while mom’s uterus is still cut open is an awkward proposition. Research also shows that less transfusion occurs during delayed cord clamping in a C-section compared with a vaginal birth, perhaps because of fewer or weaker uterine contractions to expel the placenta.5 Plus, premature babies are more likely to need immediate medical attention, and while delayed cord clamping might be helpful to these babies, medical providers are understandably anxious to care for them. All of these factors can make delayed cord clamping more challenging and less effective in the babies that could most benefit from it.

For these reasons, the recent study of cord blood milking is a welcome addition to the research on this topic. The study was a randomized controlled trial conducted at two California hospitals. It included 197 preterm infants (<32 weeks), with 154 of these born by C-section. The infants were randomized to either have delayed cord clamping of 45-seconds or to have cord milking, with babies in both groups held at or ~20 cm below the level of the placenta. In the cord milking group, the obstetrician grasped the umbilical cord close to the placenta and slid his or her hand towards the baby to push the blood along through the cord. This was repeated four times, with a couple of seconds between each to allow the cord to refill with blood.

Among the babies born by C-section, the researchers found that several outcomes were better in the babies with cord milking compared with delayed cord clamping:

  • Higher blood flow in the brain and heart (greater superior vena cava flow and right ventricular output) in the first 12 hours of life.
  • Higher hemoglobin and blood pressure during the first 15 hours of life.
  • Higher urine output in the first 24 hours of life.

These results indicate that cord milking transfers more blood to the baby than delayed cord clamping in preemies born by C-section. Greater blood flow might mean better protection against IVH. The incidence of IVH wasn’t different between the delayed cord clamping and cord milking groups in this study, but it wasn’t large enough to detect a difference.

In this study, 43 babies were born vaginally, and for them, cord milking didn’t improve outcomes over delayed cord clamping. It’s just in C-section births – and perhaps those where the baby needs immediate medical attention – that cord milking may be preferable.

I was interested in this study because cord milking has been a sort of gray area in the delayed cord clamping literature. It’s often offered as an alternative to delayed cord clamping, but as ACOG said in 2012, its safety and efficacy hadn’t been as well-studied. With this and other recent studies, that is changing. A meta-analysis published earlier this year in JAMA Pediatrics included 7 randomized controlled trials with a total of 501 babies. Among preterm babies, it found that cord milking improved hemoglobin and hematocrit, reduced the need for supplemental oxygen, and reduced the risk of IVH, all without adverse effects.6 With the addition of the current study, we have more evidence that cord milking works to improve placental transfusion, and in the specific case of preemies born by C-section, may even be preferable to delayed cord clamping.

I’ve been following the delayed cord clamping literature for some time now, and the evidence is now quite strong that babies, and especially preterm infants, benefit from receiving the blood in the umbilical cord and placenta after birth. More and more, this seems to be true whether the blood transfusion happens through patient waiting or with the help of cord milking.


  1. Katheria, A. C., Truong, G., Cousins, L., Oshiro, B. & Finer, N. N. Umbilical Cord Milking Versus Delayed Cord Clamping in Preterm Infants. Pediatrics peds.2015–0368 (2015). doi:10.1542/peds.2015-0368
  2. Rabe, H., Diaz-Rossello, J. L., Duley, L. & Dowswell, T. Effect of timing of umbilical cord clamping and other strategies to influence placental transfusion at preterm birth on maternal and infant outcomes. Cochrane Database Syst. Rev. 8, (2012).
  3. McDonald, S. J. & Middleton, P. Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes. Cochrane Database Syst. Rev. 7, CD004074 (2013).
  4. ACOG Committee on Obstetric Practice. Committee Opinion No.543: Timing of Umbilical Cord Clamping After Birth. Obstet. Gynecol. 120, 1522–1526 (2012).
  5. Aladangady, N., McHugh, S., Aitchison, T. C., Wardrop, C. A. J. & Holland, B. M. Infants’ Blood Volume in a Controlled Trial of Placental Transfusion at Preterm Delivery. Pediatrics 117, 93–98 (2006).
  6. Al-Wassia, H. & Shah, P. S. Efficacy and safety of umbilical cord milking at birth: a systematic review and meta-analysis. JAMA Pediatr. 169, 18–25 (2015).

Why Consider Delayed Cord Clamping?

I first heard about delayed cord clamping as a doctoral student in Nutrition at UC Davis. One of my professors, along with her graduate students, was conducting research on delayed cord clamping in Mexico. Their findings were exciting, and their research was eventually published in the Lancet [1]. I remember being impressed that a simple change in protocol at the birth of a baby – effectively, a non-intervention – could have a profound effect on that baby’s health.

Fast-forward five years, when I was pregnant with Cee in 2010. My OB was an attending physician at an academic hospital and very knowledgeable. However, even she was skeptical when I told her that I was interested in delayed cord clamping. I emailed her a stack of journal articles showing that, at least in an uncomplicated delivery, the benefits outweigh the risks. She was convinced, and we agreed to delay clamping, providing everything went smoothly at the delivery. In the couple of years since Cee’s birth, I think delayed cord clamping has become more mainstream and in some cases, it has become standard protocol. Still, in many hospitals, you may need to advocate for delayed clamping or at least be prepared to discuss the risks and benefits with your OB or midwife.

What exactly do we mean by delayed cord clamping?

Wikimedia Commons

Delayed cord clamping means waiting 2 to 3 minutes after the delivery of an infant before clamping and cutting the umbilical cord. During this time, blood continues to pulse from the placenta to the baby until the pulses naturally stop around 3 minutes. The transfer of blood from the placenta to the baby is most effective if the baby is placed on the mother’s abdomen or lower.

What are the benefits of delayed cord clamping?

Research has found that delayed cord clamping allows 20 to 40 mL more blood to pulse from the placenta to the newborn, carrying with it an additional 30 to 35 mg of iron [2].  As a result, babies have higher newborn hemoglobin, lower risk of anemia at birth and through 2-3 months, and higher iron status and storage through 6 months of age [2, 3].

Delayed cord clamping gives your baby more iron. Why is this important? The extra iron is stored and becomes your baby’s main source of iron until she starts eating solid foods, particularly if you breastfeed. Your baby will use that iron to form red blood cells and transport oxygen, to build muscle, and to develop her brain cells. Severe iron deficiency can cause anemia, but iron deficiency during infancy (even without anemia) also increases the risk of cognitive, motor, and behavioral deficits that can last into adolescence [4-6].

How much stored iron do babies have at birth? That depends. Because the final 8 weeks of pregnancy are most important for iron storage, babies born prematurely can really come up short in iron. Size also matters; big babies are born with more iron stores than their smaller peers. Finally, maternal iron deficiency seems to increase the risk that baby will become iron deficient later in infancy. Depending on these factors, most babies will use up their stored iron between 4 and 8 months of age, after which they’ll need to get iron from fortified formula, iron supplements, or solid foods [8].

This can pose a real problem for exclusively breastfed babies, especially since both the AAP and WHO recommend waiting until babies are 6 months old to begin introducing solid foods. Breastfed babies are at higher risk for iron deficiency than those fed formula, because formula is fortified with iron. Breast milk, on the other hand, is very low in iron. (Why is breast milk so low in iron? I ruminate about that in this post.) Although breastfed babies are very efficient at absorbing that little bit of iron, the quantity is still too small to meet their needs once their iron stores have been depleted. The AAP estimates that U.S. infants that are exclusively breastfed have a 20% risk of iron deficiency by 9-12 months of age [7].

Delayed cord clamping can give babies an extra 1-3 months of iron stores to help bridge their transition from exclusive breastfeeding to solid foods [8]. This can be especially helpful for breastfed babies that are a little slow to start solid foods. Other mammals do not rush to clamp the cord immediately after birth and therefore also get that extra dose of iron to baby before cutting her off from mom’s supply. However, immediate cord clamping does not mean your baby is destined to be iron deficient – it just increases the likelihood that she will need a boost from iron supplements and/or iron-fortified foods.

An added benefit of delayed cord clamping is that it may protect your baby from lead poisoning. One study found that in breastfed infants at risk for lead exposure in Mexico, delayed cord clamping was associated with lower blood lead levels than immediate clamping [9]. This effect is probably related to the improvement in baby’s iron stores, since iron deficiency increases lead absorption. The CDC estimates that 4 million U.S. households have children exposed to lead, so this benefit has the potential to be very relevant to these kids.

Delayed cord clamping is likely even more important for preterm infants, and in fact, is beginning to be adopted by hospitals as general protocol. Preemies are at higher risk for iron deficiency. Delayed cord clamping improves hematocrit and reduces anemia and the need for blood transfusions in these babies [10]. In one trial, it also improved motor development in 7-month-old baby boys who were born prematurely [12]. In another, it increased oxygenation of brain tissue in newborn preemies [13]. Delayed cord clamping has also been shown to decrease the incidence of intraventricular hemorrhage and late-onset sepsis in preemies [10, 11]. Many of these studies used only a 30-45 second delay in cord clamping, but these benefits were observed even with this short delay.

Are there risks to delayed cord clamping?

To date, there is no evidence for significant risks to the mother or the baby associated with delaying cord clamping by 2-3 minutes. Until 2007, early cord clamping was part of the WHO protocol for preventing maternal postpartum hemorrhage, leading many practitioners to believe that late clamping might increase maternal bleeding. However, studies have found that this is not the case [14], and the WHO modified their protocol to reflect this evidence.

Delayed cord clamping does not increase an infant’s risk of jaundice, elevated bilirubin, or the need for light therapy [2, 3]. Some studies have found that delayed cord clamping increases the risk of polycythemia in newborns. Polycythemia occurs when infants have too many red blood cells in circulation – it is the opposite of anemia. However, infants with delayed cord clamping that were diagnosed with polycythemia had no symptoms and did not require treatment. Polycythemia may be a normal outcome of delayed cord clamping in some babies, and as far as we know, it does not appear to pose a health risk in these babies [2].

One other common objection to delayed cord clamping is that it is unnecessary in a developed country, because iron deficiency and anemia are only problems in developing countries. Quite simply, this is not the case. Approximately 10% of toddlers in the U.S. are thought to be iron-deficient [15]. A study in Sweden, a country with a very low prevalence of anemia, still found benefits of delayed cord clamping in this advantaged population [3].

When is delayed cord clamping not appropriate?

If a baby is born in distress and in need of resuscitation to help her breath, delaying cord clamping takes a back seat. Babies in distress need immediate attention, and it may not be practical to care for them while the cord is still attached. To get an idea of how quickly pediatricians need to assess newborn health and take appropriate action, check out their guidelines for newborn resuscitation. As more is learned about the benefits of delayed cord clamping, pediatricians may adjust their protocols to do some procedures at the bedside, allowing the cord to remain attached. In the meantime, it is my opinion that we should let them do their jobs and not ask them to practice outside of their comfort zone when it comes to caring for newborn babies. If the cord is clamped immediately, you can make up for the lost iron by giving your baby an iron supplement or feeding her iron-rich foods when she is ready for solids.

Other resources:

The Academic OB/GYN blog, written by Dr. Nicholas Fogelson, has several articles on delayed cord clamping, as well as links to a 50-minute Grand Rounds video, which is very informative. Squintmom also has a nice, well-cited article on the topic. Links to cited studies are included in the reference list below.


1.  Chaparro, C.M., L.M. Neufeld, G. Tena Alavez, R. Eguia-Liz Cedillo, and K.G. Dewey. Effect of timing of umbilical cord clamping on iron status in Mexican infants: a randomised controlled trial. Lancet. 367(9527): p. 1997-2004. 2006. Link (abstract)

2.  Hutton, E.K. and E.S. Hassan. Late vs early clamping of the umbilical cord in full-term neonates: systematic review and meta-analysis of controlled trials. JAMA. 297(11): p. 1241-52. 2007. Link (full text available)

3.  Andersson, O., L. Hellstrom-Westas, D. Andersson, and M. Domellof. Effect of delayed versus early umbilical cord clamping on neonatal outcomes and iron status at 4 months: a randomised controlled trial. BMJ. 343: p. d7157. 2011. Link (full text available)

4.  Hurtado, E.K., A.H. Claussen, and K.G. Scott. Early childhood anemia and mild or moderate mental retardation. Am J Clin Nutr. 69(1): p. 115-9. 1999. Link (full text available)

5.  Lozoff, B., E. Jimenez, J. Hagen, E. Mollen, and A.W. Wolf. Poorer behavioral and developmental outcome more than 10 years after treatment for iron deficiency in infancy. Pediatrics. 105(4): p. E51. 2000. Link (full text available)

6.  Sherriff, A., A. Emond, J.C. Bell, and J. Golding. Should infants be screened for anaemia? A prospective study investigating the relation between haemoglobin at 8, 12, and 18 months and development at 18 months. Arch Dis Child. 84(6): p. 480-5. 2001. Link (full text available)

7.  AAP. Pediatric Nutrition Handbook. 6th ed, ed. R.E. Kleinman. Elk Grove Village, IL: American Academy of Pediatrics. 2009.

8.  Chaparro, C.M. Timing of umbilical cord clamping: effect on iron endowment of the newborn and later iron status. Nutr Rev. 69 Suppl 1: p. S30-6. 2011. Link (full text available)

9.  Chaparro, C.M., R. Fornes, L.M. Neufeld, G. Tena Alavez, R. Eguia-Liz Cedillo, and K.G. Dewey. Early umbilical cord clamping contributes to elevated blood lead levels among infants with higher lead exposure. J Pediatr. 151(5): p. 506-12. 2007. Link (abstract)

10.  Rabe, H., G. Reynolds, and J. Diaz-Rossello. A systematic review and meta-analysis of a brief delay in clamping the umbilical cord of preterm infants. Neonatology. 93(2): p. 138-44. 2008. Link (abstract)

11.  Mercer, J.S., B.R. Vohr, M.M. McGrath, J.F. Padbury, M. Wallach, and W. Oh. Delayed cord clamping in very preterm infants reduces the incidence of intraventricular hemorrhage and late-onset sepsis: a randomized, controlled trial. Pediatrics. 117(4): p. 1235-42. 2006. Link (full text available)

12.  Mercer, J.S., B.R. Vohr, D.A. Erickson-Owens, J.F. Padbury, and W. Oh. Seven-month developmental outcomes of very low birth weight infants enrolled in a randomized controlled trial of delayed versus immediate cord clamping. J Perinatol. 30(1): p. 11-6. 2010. Link (full text available)

13.  Baenziger, O., F. Stolkin, M. Keel, K. von Siebenthal, J.C. Fauchere, S. Das Kundu, V. Dietz, H.U. Bucher, and M. Wolf. The influence of the timing of cord clamping on postnatal cerebral oxygenation in preterm neonates: a randomized, controlled trial. Pediatrics. 119(3): p. 455-9. 2007. Link (full text available)

14.  McDonald, S.J. and P. Middleton. Effect of timing of umbilical cord clamping of term infants on maternal and neonatal outcomes. Cochrane Database Syst Rev. (2): p. CD004074. 2008. Link (abstract)

15.  Baker, R.D. and F.R. Greer. Diagnosis and prevention of iron deficiency and iron-deficiency anemia in infants and young children (0-3 years of age). Pediatrics. 126(5): p. 1040-50. 2010. Link (full text available)

(An earlier version of this post was published here, where it was hardly noticed. Maybe I’m too conservative for that crowd. Regardless, I’m having a hard time keeping my head above the water with teaching this term, much less find time to research and write sciency posts. I miss it. A lot. Teaching is good, but not as much fun. I’ll be back soon, promise.)