Systematic Reviews to Inform Practice, September/October 2024

Cesarean birth is a surgical intervention that can be lifesaving for the birthing person or fetus when used in the appropriate situations. However, cesarean birth is also associated with short-term risks and long-term sequelae for the birthing person, including hemorrhage, cardiac events, abnormal placentation, and uterine rupture.1 In the United States, cesareans represent 32.1% of all births.2 The primary cesarean rate, among birthing people who have not previously had a cesarean birth, is 22.5% of all births, and the primary cesarean rate among low-risk birthing people is currently 26.3%.2 Additionally, vaginal birth after cesarean remains out of reach for many individuals, representing only 14.2% of births for people who have previously had a cesarean.3 With each subsequent birth, the risks associated with cesarean birth increase.4 Healthy People 2030 set a goal of reducing the primary cesarean rate among low-risk individuals to a target of 23.6%, although this rate has remained persistently out of reach for decades.5 Therefore, in recent years, researchers and clinicians have been trying to identify interventions that can reduce the incidence of primary and all cesarean births. An intervention that has been proposed is the use of midwife-led care to reduce cesarean births. Hoxha et al sought to identify the relationship between midwife-led care and the likelihood of cesarean birth through a systematic review and meta-analysis.6 The authors registered their review protocol with Prospero and reviewed all published observational studies through May 2020. Inclusion criteria for this review were studies that reported the odds of cesarean birth with midwives involved in the care of the birthing person versus those without midwifery involvement. Bias was assessed using the quality in prognosis studies tool. The involvement of midwives in care was slightly different among studies, so the researchers identified 7 categories of midwife-involved care as an intervention, ranging from the midwife as a lead provider, to instruction provided by midwives, to the presence of midwives in an institution. They identified 18 studies that included a total of 587,144 births, ranging in years of data collection from 1987 to 2018. Included studies were published in the United States (n = 9), Brazil (n = 2), Australia (n = 2), Kurdistan (n = 1), Lithuania (n = 1), Denmark (n = 1), France (n = 1), and Kosovo (n = 1). When looking at the 7 studies that measured midwife-led care, which the authors defined as care in which the midwife was the lead health professional in the birth care, the authors found an adjusted odds ratio (OR) of cesarean birth of 0.69 (95% CI, 0.53- 0.91), or a 31% reduction in the odds of a cesarean birth when care was led by a midwife. Information is not provided in text or in figures about how many births were included in these 7 studies. When a midwife was present in the institution, the odds of a cesarean birth were reduced by 15% (OR, 0.85; 95% CI, 0.75-0.97) when compared with institutions without a midwife present. The authors also reported on single studies that demonstrated reduced odds of cesareans in midwife-attended births and midwife-provided prenatal instruction or advice about how to prepare for birth regarding hygiene and mental preparation. The authors conducted subgroup analyses of the midwife-led care group to consider a variety of additional factors that might influence the odds of cesarean birth when midwives led the care. When looking at the country where a study was conducted, they found that in the United States, the odds of a cesarean birth were reduced by 43% (OR, 0.57; 95% CI, 0.44-0.75) when midwives led the care, and in Lithuania, the odds of cesarean birth were 0.44 times as likely (95% CI, 0.27-0.61), whereas in Denmark, midwife-led care slightly increased the odds of a cesarean birth, al though the findings were not statistically significant (OR, 1.11; 95% CI, 0.98-1.26). Another subgroup analysis considered the influence of pregnancy risk category on cesarean birth when midwives led the care. The authors used the World Health Organization classification system known as Robson categories to define risk. They found that in low-risk pregnancies, defined as Robson categories 1 to 3, the odds of cesarean were reduced by half (OR, 0.50; 95% CI, 0.37-0.66), when compared with low risk pregnancies not led by midwives. The odds of cesarean birth were also reduced in Robson risk categories 1 to 5 (OR, 0.64; 95% CI, 0.52-0.81) but were unchanged when considering all risk groups (OR, 1.00; 95% CI, 0.81-1.25). When considering parity, the authors found that the odds of cesarean were reduced for nulliparous people receiving midwife-led care versus those who did not receive midwife-led care (OR, 0.57; 95% CI, 0.44-0.74). There was not a statistically significant reduction in the odds of cesarean birth for people of any parity (OR, 0.89; 95% CI, 0.68-1.17). Midwife-led care also significantly reduced the odds of a cesarean for participants with no previous cesarean (OR, 0.58; 95% CI, 0.47-0.70), cephalic presentation (OR, 0.58; 95% CI, 0.47-0.70), gestational age 37 weeks and above (OR, 0.63; 95% CI, 0.49-0.81), spontaneous labor (OR, 0.50; 95% CI, 0.37-0.66), or induced labor (OR, 0.56; 95% CI, 0.39-0.81) when compared with care that was not led by a midwife. The quality of this review is somewhat limited by the heterogeneity of the studies included, the wide range of data collection timing, and the lack of clarity on how many births are represented in each analysis. However, despite these limitations, there is a significant association that is demonstrated in this analysis that midwife-led care, and possibly simply the inclusion of midwives within the institution, can reduce the odds of cesarean births for a wide range of birthing people. At a time when institutions and policymakers are working to achieve the goal of reducing cesarean births, advocating for greater access to midwifery-led care may be an important step in achieving this goal. Human milk feeding is associated with decreased rates of neonatal mortality, infant mortality, sudden infant death syndrome, upper respiratory infections, diarrhea, otitis media, obesity, diabetes, and leukemia for the child who is fed human milk.1 There are also many positive health outcomes associated with the practice for the parent who provides human milk such as decreased rates of diabetes, hypertension, breast cancer, ovarian cancer, thyroid cancer, and endometrial cancer.1 In the United States, 83.2% of postpartum individuals initiate human milk feeding, but after one month, only 69.1% continue to provide human milk and only 45.3% are exclusively providing human milk to their infants.2 A common reason that individuals report early cessation of human milk feeding is a perception that they do not have sufficient milk supply.3, 4 Recently, research regarding the effectiveness of relaxation techniques has indicated that these modalities may assist with the success of human milk feeding, including increasing milk supply. Levene et al conducted a meta-analysis on the topic to identify the association between relaxation techniques and lactation outcomes. The authors registered their protocol with Prospero and used the Preferred Reporting Items of Systematic Reviews and Metanalyses guidelines to guide their review of the literature. Articles were eligible for inclusion in the review if they used a randomized experimental design with a control group. Studies were excluded if they used manual therapies or cognitive behavioral therapy as an intervention, as these were not considered specifically relaxation based modalities. The authors did not place restrictions on the date or language of publication. They assessed the quality of included articles using the Cochrane Risk of Bias 2 tool. Authors identified 16 articles that met their inclusion criteria with a total of 1871 participants. Included studies were conducted in India (n = 3), the United States (n = 3), Thailand (n = 2), Iran (n = 2), China (n = 2), and 1 study each from the United Kingdom, Malaysia, Spain, and Turkey. The interventions that were used in the included studies were lactation-specific guided relaxations recordings, instrumental music, singing, yoga breathing, muscle relaxation, a mindfulness app, and mindfulness training. Six of the studies only included term infants receiving human milk, whereas 10 studies included both preterm and term infants. The authors found that relaxation techniques were associated with many outcomes with moderate certainty. Relaxation techniques were associated with an increase in milk quantity when compared with usual care (standardized mean difference [SMD], 0.73; 95% CI, 0.57-0.89). They also found a small increase in milk carbohydrate (mean difference [MD], 0.15 g/100 mL; 95% CI, 0.01-0.29 g/100 mL) and an increase in milk energy (MD, 1.83 kcal/100 mL; 95% CI, 0.09- 3.57 kcal/100 mL) when using relaxation techniques. Relaxation techniques were also associated with an increase in infant weight, as measured as a z-score or change in SD score (SDS) (MD, 0.51; 95% CI, 0.30-0.72). The authors noted that a change of SDS of 0.67 is equivalent to moving from the 25th to 50th percentile on a population growth chart. Relaxation techniques were also associated with a reduction in maternal anxiety (SMD, −0.45; 95% CI, −0.67 to −0.22), reduction in maternal stress (SMD, −0.49; 95% CI, −0.70 to −0.27), and reduction in maternal diastolic blood pressure (MD, −5.9 mm Hg; 95% CI, −9.1 to −2.8 mm Hg). Some outcomes were not affected by using relaxation techniques, with moderate certainty of the lack of association. There was no difference in exclusive breastfeeding rates at 2 months of age between people who used the relaxation techniques in comparison to those who did not (relative risk [RR], 0.98; 95% CI, 0.87-1.11). The quantity of milk protein was not affected by relaxation techniques (MD, 0 g/100 mL; 95% CI, 0-0), nor was infant length (MD, 0.04; 95% CI, −0.21 to 0.29). The authors of this well-designed review note that there was considerable heterogeneity among the included studies in the types of relaxation techniques used, the frequency that the interventions were used, and the duration of the sessions. Additionally, cultural differences among the included studies’ settings could influence the acceptability of and access to these relaxation techniques. Despite these differences, the authors note that there was not significant statistical heterogeneity in most of the outcomes, suggesting that these outcomes are likely generalizable to many populations. Although further research is needed to identify which relaxation techniques are most effective at influencing human milk feeding outcomes, the meta-analysis provides good support for the positive effect of relaxation techniques on milk volume, human milk carbohydrate concentration, infant weight gain, and decreased anxiety and stress in lactating people. Considering these positive outcomes and a lack of negative outcomes associated with the use of relaxation techniques among lactating people, clinicians can consider recommending these techniques to their lactating clients as a modality to improve breastfeeding outcomes, neonatal outcomes, and maternal outcomes. Multiple sclerosis (MS) is a degenerative and chronic autoimmune disease of the central nervous system that is most often diagnosed in people 20 to 40 years of age.1, 2 It affects 2.8 million people around the world, and women are 2 to 4 times more likely to be diagnosed with MS than men.3 The most common type of MS, affecting 85% of people with the condition, is relapsing-remitting MS, which is marked by periods of neurologic symptoms followed by periods of recovery that may last months or years.4 Although there is consensus among clinicians and researchers that pregnancy is protective against MS relapse, and the risk of relapse is increased in the postpartum period, less is understood about how MS affects maternal and neonatal outcomes.5, 6 Rahmati et al sought to identify the impact of MS on pregnancy-related outcomes through a meta-analysis. The authors used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis criteria for their search. The research protocol was not registered with public registries, limiting the ability for others to confirm that the protocol was adhered to. They included any study that examined the effect of MS on maternal or neonatal outcomes. Studies were excluded if they examined the effect of MS medications on pregnancy. They used the Reporting of Observational Studies in Epidemiology guidelines to assess the included studies for bias and categorize the quality of the included studies. They ultimately identified 15 studies for inclusion in the meta-analysis, of which 12 were cohort studies and 3 were case-control studies. The studies included a total of 33,174,541 pregnant women (n = 32,191 with MS and n = 33,142,350 without MS). Included studies were conducted in the United States (n = 5), Norway (n = 2), and 1 each from Canada, Hungary, Argentina, Turkey, United Kingdom, Germany, Taiwan, and Denmark. Somewhat unusually, the authors pooled ORs and risk ratios, rather than combining the overall frequency of occurrences and creating a new set of statistics. When examining maternal outcomes, the included studies found that there was a statistically significantly increased odds of cesarean birth among women with MS when compared to women without MS (OR, 1.28; 95% CI, 1.14-1.45). There was no significant difference in the odds of preeclampsia (OR, 1.01; 95% CI, 0.88-1.16) or gestational diabetes (OR. 1.70; 95% CI, 0.33-8.62) for pregnant women with MS when compared with pregnant women without MS. When considering RR, they found similar associations. The risk of cesarean birth was higher among women with MS than those without (RR, 1.10; 95% CI, 1.03-1.16), whereas there was not a significant difference in the risk of preeclampsia (RR, 0.85; 95% CI, 0.57-1.26) or gestational diabetes (RR, 1.45; 95% CI, 0.73-2.39) between the 2 groups. The authors found that there was a significant difference in many neonatal outcomes between pregnancies that were affected by MS versus those that were not. When analyzing studies that examined ORs, the odds of preterm birth (OR, 1.39; 95% CI, 1.08-1.78), congenital malformations (OR, 1.32; 95% CI, 1.16-1.50), Apgar score less than 7 (OR, 2.13; 95% CI, 1.19-3.79), and small for gestational age newborns (OR, 1.27; 95% CI, 1.08-1.51) were all higher among neonates born to mothers with MS. However, there was no difference in the odds of being low birth weight (OR, 1.12; 95% CI, 0.80-1.55) or high birth weight (OR, 1.13; 95% CI, 0.45-2.85) between the 2 groups. When considering RR, the authors found no difference between the 2 groups for any neonatal outcome. Overall, the findings of this review indicate that pregnant women with MS are more likely than women without MS to have cesarean births. However, the reasons for these differences are unclear and may be related to neuro-muscular causes or may be related to birth location, birth provider, or patient preference. This information is unlikely to guide clinicians in their care of pregnant people with MS. The findings of the meta-analysis regarding neonatal outcomes are unclear, as the results using ORs were different from those using RR. The authors’ analysis methods, pooling ORs and risk ratios, rather than pooling individual cases, complicates interpretation and does not provide substantial guidance to clinicians caring for patients with MS. Given the prevalence of the condition in the population of childbearing people, further research is necessary to help clinicians provide comprehensive guidance to their pregnant patients with MS.

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