A comprehensive edition of each issue of Research Summaries for Normal Birth, including fuller discussions of research methods and results, will now appear in The Journal of Perinatal Education.

Ceriani Cernadas, J. M., Carroli, G., Pellegrini, L., Otaño, L., Ferreira, M., Ricci, C., Casas, O., Giordano, D., Lardizábal, J. (2006). The effect of timing of cord clamping on neonatal venous hematocrit values and clinical outcome at term: a randomized, controlled trial. Pediatrics, 117(4), e779-87. [Abstract]

Summary: In this prospective, multi-center trial researchers examined the effect of delayed cord clamping on iron-deficiency anemia and clinical outcomes in term newborns. Two hundred seventy-six healthy women with uncomplicated pregnancies were randomized to three groups: cord clamping immediately after birth, at 1 minute and at 3 minutes. Venous hematocrit (to measure anemia) and bilirubin (to measure pathologic jaundice) were drawn at 6 hours and 24-48 hours after birth. Newborn physical exams were performed by clinicians who did not know to which group the infant was assigned.

Anemia at 6 hours of age was significantly more common in newborns who were randomized to the immediate cord clamping group. There was also a significant difference at 24-48 hours of age (16.8% of newborns in the immediate clamping group versus 2.2% at 1 minute and 3.3% at 3 minutes). Significantly more infants in the 3-minute group had elevated hematocrit levels (polycythemia) at 6 hours of age. However, none of the polycythemic babies exhibited symptoms or required treatment, and this difference did not persist to 24-48 hours of age. There were no significant differences in bilirubin values, rates of neonatal adverse events, or the infants’ weight gain and rate of exclusive breastfeeding in the first month of life. There were no significant differences in maternal outcomes such as blood loss or maternal hematocrit levels.

Significance for Normal Birth: Immediate cord clamping is a practice that has been performed routinely for decades without evidence of benefit. Placental transfer of oxygenated blood, nutrients and stem cells continues for several minutes after birth. Physiologic principles suggest that the optimal transition to life outside the womb depends on this transfer. The study authors note that higher newborn iron levels at birth correlate with less likelihood of childhood anemia, a condition with long-term neurologic consequences. Some pediatricians recommend iron supplementation for breastfed infants, but it may be that by providing the full complement of iron, delayed cord clamping is the only iron supplement healthy babies need. As an added bonus, delayed cord clamping keeps babies in their mother’s arms, the ideal place to regulate their temperature and initiate bonding and breastfeeding. This may be an important first step in promoting non-separation of mother and baby after birth.

Getahun, D. Oyelese, Y., Salihu, H., Ananth, C. V. (2006). Previous cesarean delivery and risks of placenta previa and placental abruption. Obstetrics & Gynecology. 107(4), 771-8. [Abstract]

Summary: This large retrospective cohort study examined the association between history of one or more previous cesarean surgeries and the risk of placental abruption or placenta previa in a subsequent pregnancy. Data were obtained from a Missouri state-wide dataset in which siblings were linked to one another and to their biological mothers. Missouri’s vital statistics recording system has been described as a “gold standard” for its reliability and validity in previous literature.

Risk for previa in the second birth was increased 50% among women with a previous cesarean surgery. Among women with two previous cesareans, there was a two-fold increase in the risk of previa in the third pregnancy. Risk for abruption in the subsequent pregnancy was increased 30% in both the second and third births when the prior birth was by cesarean. A pregnancy occurring within the first year after giving birth by cesarean was associated with further elevations of the risk for both previa and abruption. The researchers controlled for the effects of potential confounding factors such as maternal age, race and smoking status.

Significance for Normal Birth: This study adds to the growing body of research showing strong evidence of a dose-response relationship between cesarean surgeries and placental complications in subsequent pregnancies: the more cesareans, the more complications. The doubling of risk for placenta previa in women with two previous cesareans is particularly troubling because previa in the presence of a cesarean scar is associated with placenta accreta, a complication that results in very high maternal morbidity and mortality. The long-term reproductive risks of cesarean surgery are only beginning to be understood. As the evidence of harm accumulates, it becomes ever clearer that preventing unnecessary primary cesareans is a crucial measure for protecting the health of both mothers and babies.

Fok, W. Y., Chan, L. Y., Yuet Tsui, M. H., Leung, T. N., Lau, T. K., Hung Chung, T. K. (2006). When to induce labor for post-term? a study of induction at 41 weeks versus 42 weeks. European Journal of Obstetrics & Gynecology, 125, 206-210. [Abstract]

Summary:This retrospective study compared outcomes of “post-term” pregnancies occurring when a hospital protocol required induction at 42 weeks with those occurring after the protocol was changed to require routine induction at 41 weeks. Prior to the protocol change, a routine cardiotocogram (non-stress test) was performed at 41 weeks and if normal, induction was scheduled at 42 weeks. The hospital was a university-affiliated obstetric unit in Hong Kong performing over 5000 births per year.

Routine induction of labor at 41 weeks only reduced the mean gestational age at delivery by 3 days while more than doubling the rate of labor induction in women at or beyond 41 weeks of gestation. The average length of labor was significantly longer, and use of epidural analgesia was significantly more common among “post-term” women after the protocol changed. There were no differences in maternal characteristics, mode of birth, or newborn outcomes across the two groups. Outcomes were unchanged when the researchers repeated their analyses controlling for parity.

Significance for Normal Birth: Complex hormonal signals between baby and mother allow labor to begin on its own. While this may happen for many women up to two weeks (or more) after the estimated due date, many care providers believe that routine induction at 41 weeks is associated with improved perinatal outcomes. This assertion is based on previous research that may be critically flawed.

This retrospective study is not big enough to detect differences in rare adverse maternal and infant outcomes, but it provides compelling data that suggest that inducing labor at 41 weeks is associated with very high rates of obstetric interventions. Use of pharmacologic induction agents and epidural analgesia became much more common on this obstetric unit once the clinical protocol began requiring induction of labor at 41 weeks. Labor was also considerably longer when induction was required at 41 weeks, compared with labors occurring at the same hospital prior to the protocol change. The trade-off of such excessive intervention was a mere 3-day difference in the average gestational age at birth. Women facing induction at 41 weeks need to know that waiting just a few more days will likely allow labor to start on its own and help avoid potentially harmful interventions.

WHO Multicentre Growth Reference Study Group (2006). "WHO Child Growth Standards." Acta Pædiatrica, Supplement 450. [Full Text ]

Summary: The first of a series of new pediatric growth charts have been released by the World Health Organization (WHO). The new growth standards were developed to replace existing pediatric growth charts based on growth patterns in predominantly formula-fed populations. Beginning almost a decade ago, the WHO undertook a detailed and elaborate statistical study, sampling thousands of infants from eight ethnically diverse, economically stable nations where at least 20% of women had access to breastfeeding support and followed WHO infant feeding guidelines. The healthy, term infants who participated were followed by trained researchers biweekly for 2 months, monthly up to 12 months, and bimonthly up to 24 months. An additional sample of children was followed up to 71 months. Breastfeeding support was provided as needed. Data were collected on infant growth patterns and achievement of motor skills.

The resulting infant growth standards offer pediatric providers and parents the first evidence-based information on how children should grow under optimal conditions. The researchers found that there was very little ethnic variability in average growth or achievement of motor skills, suggesting that poverty and sub-optimal nutrition are responsible for previously observed regional variability in infant growth.

Significance for Normal Birth: The WHO infant growth charts are an important step in positioning breastfeeding as the norm and reversing decades of erroneous advice to parents of breastfed infants who were told that their infants were failing to thrive because they gained weight more slowly than formula fed infants. Now, more formula fed babies will be seen to “fall off the curve” by gaining weight too rapidly, an important predictor of childhood obesity.

The results of the WHO Multicentre Growth Reference Study provide solid evidence that breastfeeding contributes to the optimal growth and motor development of infants. Interventions in normal birth, including cesarean surgery and unnecessary separation of mothers and babies impede women’s ability to initiate successful breastfeeding with their newborns thereby contributing to less than optimal infant growth and development.