Science & Sensibility

In preparing the Home Birth chapter for the forthcoming second edition of Obstetric Myths versus Research Realities, I have literally just finished reading the entire body of literature on planned home birth. Just last week, I said to my co-author, Henci Goer, “frankly, I’m pretty underwhelmed by the quality of most of the studies.” (Though, don’t get me wrong, I still believe that the preponderance of the evidence strongly favors the choice of planned home birth.) But for the second time this year, an exemplary study on planned home birth has been released. Together with the Dutch study released in April, the current study ushers in a new era of home birth evidence that addresses many of the methodological limitations of previous home birth research. Seriously, folks, these two studies raise the bar.

Researchers in Canada analyzed the outcomes of all women who were intending to give birth at home at the onset of labor in British Columbia between 2001-2004 (n=2899 women). Data were obtained from the provincial database that collects information on all births and is cross-referenced with the national vital statistics (birth/death certificates) database. The researchers compared outcomes in the planned home birth group with those of two groups of women who met eligibility requirements for home birth but planned to give birth in hospitals instead. One of the two comparison cohorts had planned hospital births with midwives (n=4752); the other with physicians (n=5331).

Consistent with many other studies comparing planned home with planned hospital birth, the results showed comparable perinatal mortality rates, less serious morbidity for both women and infants, and lower use of obstetric technology in planned home births. Here are the results, as presented in the study’s abstract:

The rate of perinatal death per 1000 births was 0.35 (95% confidence interval [CI] 0.00–1.03) in the group of planned home births; the rate in the group of planned hospital births was 0.57 (95% CI 0.00–1.43) among women attended by a midwife and 0.64 (95% CI 0.00–1.56) among those attended by a physician. Women in the planned home-birth group were significantly less likely than those who planned a midwife-attended hospital birth to have obstetric interventions (e.g., electronic fetal monitoring, relative risk [RR] 0.32, 95% CI 0.29–0.36; assisted vaginal delivery, RR 0.41, 95% 0.33–0.52) or adverse maternal outcomes (e.g., third- or fourth-degree perineal tear, RR 0.41, 95% CI 0.28–0.59; postpartum hemorrhage, RR 0.62, 95% CI 0.49–0.77). The findings were similar in the comparison with physician-assisted hospital births. Newborns in the home-birth group were less likely than those in the midwife-attended hospital-birth group to require resuscitation at birth (RR 0.23, 95% CI 0.14–0.37) or oxygen therapy beyond 24 hours (RR 0.37, 95% CI 0.24–0.59). The findings were similar in the comparison with newborns in the physician-assisted hospital births; in addition, newborns in the home-birth group were less likely to have meconium aspiration (RR 0.45, 95% CI 0.21–0.93) and more likely to be admitted to hospital or readmitted if born in hospital (RR 1.39, 95% CI 1.09–1.85).

What makes this study stand out from most  of the rest:

1. Planned home births occurred in a context with relatively rigid guidelines for eligibility (see the full-text of the article to view the guidelines). These guidelines, determined by the Ministry of Health, were applied to women planning hospital births in order to construct the comparison cohorts. This increases the likelihood that, medically at least, the populations were similar. In addition, participants in the home birth group were matched with participants in the physician-attended hospital birth for the following parameters: year of birth, parity, single parent (yes or no), maternal age, and the hospital where the midwife conducting the index home birth had hospital privileges.

2. The authors made the cohorts more similar with statistical analysis – first, controlling for confounding variables and second, testing and retesting their data with different assumptions and exclusions. (Referred to as “sensitivity analysis,” this is a mechanism used by researchers to make sure their findings hold up under various circumstances and are unlikely therefore to be biased.)

3. The researchers isolated the effect of the birth setting itself by comparing midwife-attended home birth with midwife-attended hospital birth. In fact, the same group of midwives cared for women in both settings, so differences are likely to be related to the setting and its protocols and technological accoutrements (or lack thereof) rather than differences in the providers who actually provide the care.

4. According to the study authors, midwives in British Columbia are required to offer medically eligible women a choice of planned home or hospital birth. While women still must self-select to one choice or another, this certainly mitigates some bias. Self-selection bias refers to the possibility that individuals who, in this case, select different birth settings or providers, may be different in ways that are not measured but that nonetheless affect the likelihood of important outcomes. For example, women who choose home birth may have better nutrition, stronger family support systems, or a more positive outlook on labor and birth. But these differences may be less pronounced when the group selecting home birth showed up at the same prenatal clinic as all of the rest of the women and were (perhaps enthusiastically) presented the option of birthing at home. Contrast this with the population of women in parts of the United States who must actively seek out home birth, pay out of pocket, and be told that no physician will willingly consult if medical problems arise so they must settle for the emergency room, whether or not the transfer to the hospital is urgent. (The vast majority of transfers from home to hospital are not.) Only the most dedicated are likely to choose such an option.

5. Although the study was retrospective (meaning data were collected after the fact), data were obtained from province-wide databases to which care providers are obligated to enter data on each and every birth. In addition, these databases have been tested for the reliability of the data (to detect the possibility that certain outcomes are systematically underreported or overreported). Reliability was above 97% for all outcomes. Fewer than 1 in 10,000 records were missing. *

The only thing I did not see in the report that I would have liked to is a detailed description of the circumstances of each fetal or newborn death. These descriptions often provide clues as to whether small differences in perinatal mortality could have been attributed to the planned place of birth and whether and how they might have been averted.

No study of home birth will be perfect, but large perinatal databases and systems that integrate rather than marginalize home-birth midwifery have helped to achieve the “scientific rigor” that the American College of Obstetricians and Gynecologists has called for. And the results are looking very good indeed.

* denotes edited text. Click “read more” to view the original version. Read more…

Amy Romano Lamaze news, Uncategorized, new research, practice guidelines, sensibility, systematic review cesarean, home birth, interventions, midwives, practice variation

Advocates for evidence based care feel our ears perk up when we hear about a new Cochrane systematic review. Cochrane Review = Evidence! Right? Indeed, systematic reviews represent the top of the “evidence pyramid” and Cochrane systematic reviews are the gold standard for their rigor and transparency. A Cochrane review can even conclusively settle important clinical controversies.

But sometimes Cochrane reviews leave us with more questions than answers.

Last week, the Cochrane Library released a systematic review evaluating the effectiveness of intrapartum antibiotics for known maternal group B streptococcal (GBS) colonization. And it’s a hot mess.

The four included trials that compared IV antibiotics with no treatment in labor collectively had only 500 participants, which we automatically know is far too small to find statistically significant differences in a condition that affects 1 in 2000 newborns, and results in death or long-term complications even less frequently. But small sample sizes were the least of the problems here. The reviewers noted several other problems with the trials:

• In one study, researchers tracked their findings and halted the trial as soon as a significant difference was found (favoring treatment with antibiotics). This is a blatant form of bias – it is like flipping a penny until you get heads 5% more often than you got tails. If you keep flipping long enough (or stop flipping soon enough) you’ll be able to find that 5% difference simply by chance.
• In the same study, researchers changed to a different statistical test that allowed them to achieve statistical significance with their data, when the originally planned (and more appropriate) test would have produced a nonsignificant finding.
• None of the studies used placebos, so women, care providers, and hospital staff knew which women received antibiotics and which did not. This may have altered treatment of the women or the babies, possibly in ways that would make no antibiotics appear safer (for instance, avoiding or delaying membrane rupture in a woman who is GBS+ but not getting antibiotics).
• One study excluded women who developed fevers in labor. GBS colonization can cause maternal fever and newborn sepsis, so excluding these cases makes no sense.
• Some women included in the studies were likely GBS negative because methods used to determine GBS status were inadequate
• Outcomes were poorly defined.
• Data on a substantial proportion of women and babies were missing.
• Groups were mysteriously differently sized.
• Need I go on?

The Cochrane reviewers, in my opinion, did a respectable job with what they had, but what they had was garbage and as the saying goes, “Garbage in, garbage out.” You can’t make reliable conclusions out of a bunch of bad research, even if you’re a Cochrane reviewer.

So what were the findings?

Three trials, which were around 20 years old, compared ampicillin or penicillin to no treatment and found no clear differences in newborn deaths although the occurrence of early GBS infection in the newborn was reduced with antibiotics.

More, better research is needed, but the Cochrane reviewers are not optimistic:

Ideally the effectiveness of intrapartum antibiotics to GBS colonized women to reduce neonatal GBS infections should be studied in adequately sized double blind controlled trials. The opportunities to conduct such trials have likely been lost as practice guidelines have been introduced in many jurisdictions. (p. 11)

Source: Centers for Disease Control and Prevention. http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5111a1.htm

In the meantime, women should be aware that other evidence, albeit not from randomized controlled trials, suggests that antibiotic treatment reduces deaths from early onset GBS disease in newborns. According to the Centers for Disease Control and Prevention, a steady decline in GBS disease has been seen in individual institutions, in the whole U.S. population, and in other countries as antibiotic use has risen. But these population-level data cannot tell us whether antibiotics or some other factor  caused the decline.

What other advice can we share with women?

1. Be aware that antibiotics are not harmless. Severe allergic reactions are possible, and antibiotic use in labor can result in thrush (candida infection) which causes painful breastfeeding and sometimes early weaning. We do not know other possible harmful effects because they have never been studied adequately or at all.
2. No study confirms the effect of labor practices on GBS infection in newborns, but here we can use our common sense. Care providers should avoid or minimize sweeping/stripping membranes before labor, breaking the bag of waters, vaginal exams, and other internal procedures, especially those that break the baby’s skin and can be a route for infection. These include internal fetal scalp electrodes for fetal heart rate monitoring and fetal blood sampling.
3. Keep mothers and babies skin-to-skin after birth. This exposes the baby to beneficial bacteria on the mother’s skin, facilitates early breastfeeding, and lowers the likelihood that the baby will exhibit signs or symptoms that mimic infection, such as low temperature or low blood sugar, which could cause the need for blood tests or spinal taps to rule out infection.

Citation: Ohlsson A, & Shah VS (2009). Intrapartum antibiotics for known maternal Group B streptococcal colonization. Cochrane database of systematic reviews (Online) (3) PMID: 19588432

Amy Romano systematic review antibiotics, bias, flawed, GBS, interventions, IVs, newborns, no separation, systematic review, tests in pregnancy

I wrote recently about the myth that birthing without an epidural is akin to needless suffering.  Now we expose another myth: that modern U.S. hospitals offer the full range of labor pain relief options. Many of them don’t. If the nurses are not trained or motivated to provide effective comfort measures, or if staffing patterns or hospital policies preclude them from offering this style of care, then women cannot access many safe and effective pain relief methods. The menu of choices should include far more than two: an epidural or a plate of brownies and a prayer.

In 2002, Childbirth Connection commissioned a series of systematic reviews on labor pain management, a body of literature that still offers the best available evidence on the safety and effectiveness of various pain management methods. They also conducted the Listening to Mother’s Surveys, in which we discover that some of the pain relief methods women appreciated the most were used the least. It is not surprising that the first conclusion Childbirth Connection offers in their summary of the evidence is this:

A woman’s labor pain relief options depend in large measure on where and with whom she chooses to give birth; women in other western industrial nations appear to have more options for labor pain relief than women in the U.S.

Don’t get me wrong – I’m all for treating nurses well and showering them with well-deserved gifts (brownies! mani/pedi! flowers!). But our maternity care system itself – not gifts from laboring women – should encourage nurses to provide excellent labor support and ensure access to the full range of safe pain relief options for women. And to all the women out there wanting a natural birth: rather than taking The Doctors’ word for it, try these tips for a healthy, safe, and natural birth from Lamaze International. They’re time-tested, supported by plenty of research, and out-perform any plate of brownies (even the gooey melt-in-your mouth kind)!

Nurses and Nurse Managers: Want to improve the labor support skills of your nursing staff and help your nurses obtain continuing education hours? Bring Lamaze International’s Labor Support Specialist Workshop to your facility!

Amy Romano research for advocacy, systematic review epidurals, maternity care systems, nurses, pain

This week, media outlets shared the news of a new Cochrane review that concludes upright positions are beneficial because they shorten labor by about one hour. The birth blogs have been buzzing about this, and the consensus is that we should feel delighted and vindicated to have the scientific evidence to prove what women and midwives have always known.

Cochrane reviews synthesize all of the research on a particular topic, and because the reviewers bring together and analyze all of the data from many studies, the study population gets very big. Big populations yield greater statistical power and often (but not always) more reliable findings.

Prior to this Cochrane review there was a large body of literature on movement in labor, including a good sized U.S. randomized controlled trial. There was even another systematic review! But this body of research never consistently supported the hypothesis that movement improved labor and birth outcomes. Now we have a Cochrane review, which is the gold standard for evidence-based practice.  So we can put the evidence-based “stamp of approval” on freedom of movement.

But, were we any less justified in endorsing freedom of movement before the Cochrane?

Read the full post and leave comments at The Giving Birth with Confidence Blog.

Amy Romano new research, sensibility, systematic review freedom of movement, labor progress, pain, systematic review

Often, the closer I look at a study, the less confident I become about the results. I’ve learned that you can’t always trust a paper’s title or abstract, and media coverage of new studies can be woefully misleading, even when it is not carefully orchestrated by those with a vested interest (which it often is). Being advocates for “evidence-based care” means not just knowing that a study has been published, but knowing whether that study is any good, and in what circumstances (if any) the results are relevant and reliable. It also means having our guard up against deeply flawed studies that shape policy and practice despite their limitations. (Henci Goer has done a fantastic job deconstructing some of these influential studies in her series, When Research is Flawed.)

A systematic review synthesizes all of the literature on a given topic, using rigorous criteria for which studies will be included. For instance, Cochrane systematic reviews are typically confined to randomized, controlled trials in which there is no evidence that the randomization process has been intentionally subverted. For this reason, Cochrane reviews are considered the “gold standard” of evidence.

Read the full post and leave comments at The Giving Birth with Confidence Blog.

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