for Normal Birth

Routine Suctioning Before Delivery of the Shoulders of Meconium-Stained Infants Does Not Prevent Meconium Aspiration Syndrome

Vain, N. E., Szyld, E. G., Prudent, L. M., Wiswell, T. E., Aguilar, A. M., & Vivas, N. I. (2004). Oropharyngeal and nasopharyngeal suctioning of meconium-stained neonates before delivery of their shoulders: multicentre, randomised controlled trial. The Lancet, 364(9434), 597-602. [Abstract]

Summary: This is the first randomized controlled trial to assess the widespread practice of oropharyngeal (mouth) and nasopharyngeal (nose) suctioning before birth of the shoulders in deliveries complicated by meconium-stained amniotic fluid (MSAF) for prevention of meconium aspiration syndrome (MAS). The study took place in 2000-2001 in 12 hospitals – 11 in Argentina and 1 in the United States. Women delivering vaginally or by cesarean section with MSAF at term (= 37 weeks) and fetuses with cephalic (head-down) presentations were included. Women who were unable to be randomized before delivery or whose obstetricians refused to participate were excluded.

Infants were randomly selected to receive suction (n=1263) or no suction (n=1251). Following birth, care was provided according to Neonatal Resuscitation Program guidelines (tracheal suctioning in non-vigorous infants) in both groups. MAS was carefully defined and excluded infants with congenital malformations of the respiratory system or heart. There were no differences between the groups in demographic variables, nor in the frequencies of thick meconium, cesarean delivery, or abnormal fetal heart rate during labor.

The researchers did not detect any difference in MAS between the two groups (15% suction, 14% no suction). Similarly, no differences were found in the rates of mechanical ventilation, neonatal death, or any other intrapartum or neonatal outcome studied. The authors discuss the evidence suggesting that MAS is a process that develops in utero. They conclude that suctioning before birth of the shoulders does not prevent MAS and suggest revision of current guidelines that call for this practice.

Significance for Normal Birth: Any intervention in the normal physiologic process of birth has the potential to cause harm and must only be used when the evidence shows clear benefits outweighing these risks. The practice of intrapartum suctioning to prevent MAS in the presence of MSAF is the standard of care in virtually all birth settings. With up to 10 percent or more of infants born through MSAF, the implications of routine suctioning are significant. Known risks of suctioning include breathing disruptions, cardiac irregularities, delays in resuscitation, and local trauma that may contribute to feeding problems.

In maternity care, new interventions continue to be incorporated into standard practice despite incomplete or poor-quality evidence supporting their use. Meanwhile, efforts to change routine practices in the face of good quality evidence showing lack of benefit or clear harm face significant obstacles. Despite the evidence presented in this new study that routine suctioning of meconium-stained infants is not beneficial, the practice is likely to continue. Normal birth advocates play an essential role in changing practices that introduce new risks without improving outcomes. [Abstract]

Uterine Rupture After Previous Cesarean Section Rarely Causes Serious Consequences

Guise, J.-M., McDonagh, M. S., Osterweil, P., Nygren, P., Chan, B. K. S., & Helfand, M. (2004). Systematic review of the incidence and consequences of uterine rupture in women with previous caesarean section. BMJ July 3, 329(7456), 19-25. [Abstract]

Summary: This systematic review of the literature describes the additional risks of symptomatic uterine rupture and the serious consequences of such ruptures when women who have undergone a previous cesarean section choose a trial of labor (TOL) rather than elective repeat cesarean delivery (ERCD). The researchers undertook a comprehensive review of the literature to identify all relevant studies. The quality of the studies was determined using established criteria and studies receiving poor quality ratings were excluded. Of the 71 potentially eligible studies, 50 were excluded for poor quality ratings. Two large population-based retrospective studies, 15 prospective cohort studies, 2 case-control studies and 2 case series were included in the review. Symptomatic uterine rupture was defined as rupture diagnosed surgically following signs or symptoms of uterine rupture, such as fetal heart rate abnormalities or maternal bleeding. Asymptomatic rupture, on the other hand, was defined as scar dehiscence or uterine wall defect discovered during uterine exploration but not causing symptoms.

The reviewers found that, for every 10,000 women attempting TOL instead of ERCD, there are 27 additional symptomatic uterine ruptures, 1.4 additional perinatal deaths associated with rupture, and 3.4 additional rupture-related hysterectomies. Using these rates of additional risk, it would take 370 elective repeat cesarean deliveries to prevent one symptomatic uterine rupture, 7142 to prevent one rupture-related perinatal death, and 2941 to prevent one rupture-related hysterectomy. The authors conclude that most uterine ruptures do not have serious consequences and suggest that inconsistent terminology and other limitations in the available literature may lead patients and clinicians to perceive greater risk than what the best quality evidence supports.

Significance for Normal Birth: The rate of normal birth has decreased sharply as surgical birth has become more common. A recent increase in cesarean section rates can be attributed in large part to a decrease in women attempting vaginal birth after cesarean section. This trend is related to recent evidence that points to excess risk of uterine rupture in women choosing TOL over ERCD. While this study confirms this excess risk, it also points to serious inconsistencies and methodological problems in the evidence that many women and their providers have relied upon. Good quality evidence should be not only methodologically sound but also measure clinically significant outcomes. Combining symptomatic uterine rupture, which is very rare but can have devastating consequences, with asymptomatic rupture, which is usually an incidental finding and does not lead to poor outcomes, may mislead some women to choose ERCD when they would otherwise be inclined to pursue a normal birth. [Abstract]

Prelabor Rupture of Membranes Occurs Most Often Around Midnight

Ngwenya, S., & Lindow, S. W. (2004). 24 hour rhythm in the timing of pre-labour spontaneous rupture of membranes at term. European Journal of Obstetrics & Gynecology and Reproductive Biology, 112(2), 151-153. [Abstract]

Summary: This prospective observational study was designed to determine whether a 24-hour rhythm exists in the timing of prelabor rupture of membranes (PROM). Women with confirmed PROM at term (= 37 weeks) and not in labor within 4 hours (n=196) were included in the trial, which took place from June 2001 to January 2002 in a hospital setting in the United Kingdom. Women with multiple pregnancies, vaginal bleeding, or suspected chorioamnionitis (womb infection) were excluded. All participants denied having had sexual intercourse in the 12 hours before rupture of membranes.

The researchers found a significant 24-hour rhythm, with 33.2 percent of incidences of PROM occurring between midnight and 4:00 AM (p < .0001). There was no discernible rhythm in the timing of onset of labor after PROM. Cesarean delivery was most common among women who experienced PROM between 4:00 PM and midnight (p < .05). The timing of onset of labor was not related to the time of day when PROM occurred. Data related to the frequency of labor induction were not reported.

The study authors discussed various potential mechanisms that might explain the 24-hour rhythm of PROM, including known enzymatic activity that results in the break down of fetal membranes, pressure changes related to “Braxton-Hicks” contractions, and inflammatory processes.

Significance for Normal Birth: Labor and birth are normal physiologic processes, but surprisingly little is known about the exact mechanisms of the onset of labor and rupture of membranes. As we learn more about the physiology of labor and birth, we can potentially avoid the misuse of technological interventions meant to mimic or enhance the processes. Women who experience prelabor rupture of membranes often undergo induction of labor which carries with it significant risks. A natural rhythm of rupture of membranes may affect the efficacy or practicality of introducing interventions designed to start labor. [Abstract]

Midwifery Process Places Emphasis on Keeping Birth Normal

Kennedy, H. P., & Shannon, M. T. (2004). Keeping birth normal: research findings on midwifery care during childbirth. JOGNN - Journal of Obstetric, Gynecologic, & Neonatal Nursing, 33(5), 554-560. [Abstract]

Summary: This qualitative study describes key aspects of the process of midwifery care. Eleven certified nurse-midwives completed interviews about how they achieve the objective of being “with women” in pregnancy and childbirth. These midwives had been previously identified as “exemplary” based on their clinical expertise and midwifery philosophy, and had participated in a study where “support for normalcy” was identified as central to the midwifery process. Narrative analysis was used to examine the responses in the current study. A series of coding and interpretive decision making allowed the researchers to organize and analyze the midwives’ narratives. The research team was comprised entirely of midwives, but secondary analysis was done by non-midwife researchers to enhance validity of the study.

The theme about which the midwives spoke most frequently was “support for normalcy.” The researchers analyzed this theme and found several elements that contributed to this process: 1) belief in the normalcy of birth, 2) tolerance of wide variations of normal within a defined circle of safety, 3) belief in the woman’s strength, 4) The physical act of being present with women, and 5) teaching students to believe and trust in normal birth. Through their narratives, the midwives described the task of balancing their belief in normalcy with vigilant assessment to help determine when technological intervention was truly needed. The study authors discuss limitations to their study, including the participants’ knowledge of the purpose of the study and the likelihood that the midwives did not comprise a representative sample. But they conclude that midwives’ “finely tuned balance of navigating between low- and high-technological worlds may hold clues to the differences between midwifery and medical models of care.

Significance for Normal Birth: This study illuminates aspects of the midwifery model of care that support the normalcy of birth. While the study does not compare the midwifery process with that of physicians, it identifies frustrations of exemplary midwives who work within a medical model of care, suggesting that our system does not address birth as a normal physiologic process. It appears very likely from the results of this study that normal birth is most likely to be achieved when midwives attend women in labor and birth. However, efforts must be made to enhance the ability of midwives to practice within a midwifery model, unencumbered by protocols and practice standards that regard birth as a pathologic process. [Abstract]

Amniotic Fluid Index a Poor Predictor of Perinatal Outcome in High-Risk Pregnancies Compared With Single Deepest Pocket Technique

Magann, E. F., Doherty, D. A., Field, K., Chauhan, S. P., Muffley, P. E., & Morrison, J. C. (2004). Biophysical profile with amniotic fluid volume assessments. Obstetrics & Gynecology July, 104(1), 5-10. [Abstract]

Summary: In this prospective randomized controlled trial, researchers studied the impact of two common methods of amniotic fluid assessment on the rates of cesarean section for fetal distress and other outcomes among women at high risk for adverse pregnancy outcomes. Women who were being assessed with weekly biophysical profiles (BPPs) for pregnancy complications or preexisting maternal disease were randomized to receive a standard BPP (n=273), in which the “single deepest pocket” technique is used to assess fluid volume or the modified BPP (n=264), in which the amniotic fluid index (AFI) is used. Oligohydramnios (low amniotic fluid) was defined as single deepest pocket < 2cm x 1cm or AFI = 5cm. Women with multiple pregnancies or known fetal anomalies were excluded. Labor was induced immediately when oligohydramnios was diagnosed in pregnancies at or beyond 34 weeks gestation or after administration of corticosteroids to promote fetal lung maturity in pregnancies at fewer than 34 weeks gestation. Maternal characteristics, including the medical indication for BPP testing, were similar in the two groups.

Women monitored by AFI were twice as likely to be induced for a diagnosis of oligohydramnios (30 percent versus 15 percent, p < .001) and were also more likely to undergo cesarean section for fetal distress (13 percent versus 7 percent, p = .014). There were no differences between the two groups for any neonatal outcomes. In a follow-up analysis of cases where oligohydramnios was detected by one of the two techniques, there was no difference in the rate of cesarean section for fetal distress between the groups, suggesting that the specificity of the AFI in predicting fetal distress is poor. The study authors conclude that, in high-risk pregnancies being serially monitored by BPPs, using AFI rather than the single deepest pocket technique results in more interventions and greater risk to the mother without improving any perinatal outcomes.

Significance for Normal Birth: In normal birth, labor begins on its own. But sometimes labor induction is necessary for medical reasons, including oligohydramnios. Unfortunately, the tools available for detecting oligohydramnios often result in over-diagnosis of the condition, resulting in increased interventions without improved outcomes. This study compares the two common methods for assessing amniotic fluid volume and finds that the single deepest pocket technique is the better test for determining which women might benefit from interventions for the management of a high-risk pregnancy complicated by oligohydramnios. [Abstract]