Читать книгу Let Them Eat Dirt - B. Brett Finlay - Страница 14

4:Birth: Welcome to the World of Microbes

The Best Laid Plans

At 3:50 a.m. a week before her due date, Elsa realized she was in labor. She was sleeping (sleeping should really have a different name in late pregnancy, as it is just not the same thing) when her water broke, alerting her and her startled husband that it was time. Soaking wet, they nervously laughed at the realization that they were going to meet their baby boy soon. They had a hospital delivery plan written down—labor in a bathtub, “laughing gas” for pain management, clear communication about interventions—and then, when the contractions became closer together, they would calmly put on comfortable clothes, gather their already-packed hospital bag (which included magazines, an iPad to serve as a music player and video camera, a massage device, and a heating pad), gather snacks and energy drinks, phone the grandparents, and drive to the hospital. The infant car seat had been installed in their car for about a month, and they had even practiced driving the route they were going to take. They already knew the best place to park in the hospital parking lot and the exact location of the maternity ward. Elsa and her husband had it all covered . . . or so they thought!

The first thing that kiboshed their perfect plan was having her water break before feeling contractions, also known as PROM (premature rupture of membranes). Elsa wanted to labor at home, but she knew that she had to go to the hospital right then. When the water breaks, the bag full of amniotic fluid, which keeps the baby protected, ruptures. It’s not unusual for it to occur before labor, with 1 in 10 women experiencing that, but babies need to be monitored when this happens due to an increased risk in complications, such as an umbilical cord prolapse or an infection.

Within fifteen minutes they were out the door. They got dressed, grabbed the bag, forgot the snacks (oops), and decided to call their parents on the way to the hospital. It took Elsa another ten minutes to find a not-too-uncomfortable position to sit in the car, and just then, she started to feel her first real contraction. It was overwhelmingly strong. “If this is early labor,” she thought, “I won’t be able to deal with the pain.” Elsa’s husband, Paul, had previously volunteered to monitor her contractions. He had an app in his phone that would time contractions, and allow them to give each one an intensity score from one to five. As soon as Paul noticed the first contraction he reached for his phone and started to record its duration. Excited, he then asked Elsa: “How would you rate that contraction, babe?” With her gaze and voice lost, Elsa slowly opened her hand and showed him five fingers. “A five?” Paul said, “That can’t be, we just got started!” And with the look that so many husbands have experienced during their wives’ labor, Elsa just said, “Drive!”

By the time they reached the hospital, Elsa was already dilated five centimeters (halfway there) and in intense labor. “Forget the *&#^$ plan!!” she yelled. “I WANT AN EPIDURAL NOW!!” The nurse strapped a monitor to Elsa’s belly to measure the baby’s heart rate and Elsa’s blood pressure. On the next contraction (they were coming three minutes apart now) the nurse noticed that the baby’s heartbeat had dropped, not a lot, but enough to bring the obstetrician in to have a look. Then, just as the nurse was about to put an IV in Elsa’s arm, the baby started squirming around, causing Elsa even more pain. Worse yet, the baby’s heart rate dropped significantly. The obstetrician monitored the baby during the next sets of contractions and surmised that the baby must be pinching the umbilical cord. “We have to get him out now,” the doctor said.

In what felt like hours but was only a few minutes, Elsa was rushed to the operating room and given spinal anesthesia for the C-section, after which they allowed Paul in the room. Elsa and Paul were both terrified.

However, very soon thereafter they heard the sweetest sound of their baby boy, Elijah, crying. A pediatrician and nurses quickly took Elijah to make sure he was all right (he was). After weighing and measuring him, they brought him to his parents, who were crying with relief, excitement, and love. “So much for the best laid plans,” said Paul. Their cries turned into laughs as they realized that nothing had gone according to plan. It didn’t matter . . . their baby was here and everyone was okay. Paul pulled out his phone, took the first picture of Elsa and Elijah, and sent it to the proud new grandparents, just over two hours after Elsa’s water had broken, back in their bedroom.

Cesarean Epidemic

Although births come in different circumstances, durations, and outcomes, they have two things in common. First, just like with Elsa and Paul’s experience, they seldom go as planned; births are unpredictable. Second, no one ever forgets when, how, and what it feels like to give birth. No other event in life compares in intensity and emotional impact. Biologically speaking, having a baby is the pinnacle of our existence, yet the human birth experience is very painful and often risky. In fact, compared to apes, human birth is longer and more perilous. Elsa’s labor was unusually short at only two hours, but most first births average ten hours, and many are even longer. In addition, about 1 in 250 mothers carry a baby with a head too big to fit through the birth canal, requiring a cesarean section (C-section). One would think evolution would have favored easy deliveries, yet our bodies have not greatly improved on the process. Before the development of modern obstetrical medicine, there were about 70 deaths per 1,000 births. Those statistics have improved, but still, to this day, 500,000 women die annually worldwide from complications during childbirth. Why is human birth such hard and hazardous work?

Scientists believe that our births are more complicated because of the “human condition”: we walk on two legs and have very big brains. Walking on two legs was truly advantageous to our human ancestors; they had their arms free to reach for fruit and other foods, they could carry items (babies included), they could hunt and craft tools, and they could look above the vegetation by standing upright. However, this advantage came with the anatomical price of narrower hips in order to achieve better balance and support the body’s weight on two legs. Another aspect that makes humans unique is the large size of our brains. Thanks to our developed brains, humans can do math, build skyscrapers, and read books. Big brains (and, consequently, big heads) plus narrow hips? Any human can do this math: this causes the level five painful contractions Elsa was feeling and the medical need for C-sections.

C-sections are a medical miracle in terms of their ability to save the lives of so many mothers and babies. Try to imagine how much scarier Elsa’s birth would have been had a C-section not been an option. Elijah’s umbilical cord had twisted, preventing him from getting enough oxygen and blood flow. Elijah could have suffered a serious brain injury or even died from asphyxia if a trained doctor hadn’t been able to pull him out surgically. A hundred years ago, dying during birth was a lot more common for both mothers and babies and modern C-sections played a pivotal role in changing this.

The history of when and where the first C-sections took place is a bit murky, but there are accounts of C-sections dating as far back as Ancient Greece. It is commonly believed that the name of this surgical procedure originates from the birth of the Roman emperor Julius Caesar. Regardless of whether this is true or not, Roman law decreed that all dying or dead birthing mothers had to be cut open in an attempt to save the child. Unfortunately, mothers rarely survived these early medical procedures and they were performed only as a last resort. Once anesthetic and antiseptic practices became the norm, C-sections became a much safer procedure and were used to save many lives. At the beginning of the twentieth century, for every 1,000 births, 9 women and 70 babies would die during childbirth, compared to 0.1 women and 7.2 babies today. That’s more than a 90 percent reduction in mortality, a true triumph for modern medicine.

Still, for many decades C-sections were performed only when it was medically necessary: if the lives or health of the mother and/or the baby were at risk. However, towards the last quarter of the twentieth century, C-section rates skyrocketed. In 1970 the C-section rate was 5 percent in the US, rising to almost 25 percent by 1990 and to 33 percent in 2013. It has gone from a rate of 1 in 20 babies to 1 in 3 babies in the span of forty years. Canada’s C-section rate is slightly lower at 27 percent, but it has still experienced a 45 percent increase since 1998.

Unlike the initial decrease in mother and infant mortality, the surge in C-section rates experienced in the past thirty-five years did not bring an improvement in mortality or morbidity (disease) rates. On the contrary, a C-section performed without a medical indication, also known as an elective C-section, is riskier than a vaginal birth. A C-section is a major surgical procedure that poses an increased risk of blood loss and infection for the mother. Also, any mother that has birthed via C-section can attest that healing takes much longer than a vaginal birth, not to mention the limited mobility of the new mother, who must let the incision to her abdomen heal; it’s harder to hold the baby, to get up to change diapers (wait—maybe this is a plus), and sometimes even to breastfeed. Since 1985, the World Health Organization (WHO) has determined that the ideal rate for C-sections should be between 10–15 percent. Newer studies show that the number is likely closer to 10 percent. When C-sections rates approach 10 percent in a population, mortality surrounding birth decreases. But when the rates rise above 10 percent, mortality does not improve.

There are many explanations for this unnecessary but widespread increase in C-sections, and discussing them and their complexities are probably the subject for an entirely separate book. Suffice it to say, C-section rates are still increasing, and they are becoming epidemic and an emerging global health issue. Many experts disagree with this view and support the current rate of C-sections, because even if they are riskier than natural births, they are still very safe procedures. Modern obstetricians are extremely skilled in this surgery, and most complications that result from it, which are rare, can be treated with good outcomes in a hospital setting. There are maternal advantages associated with an elective C-section as well, including a reduction in urinary incontinence (loss of bladder control), avoidance of labor pain, reduction of fear and anxiety related to labor, and the overall convenience of planning the timing of birth. To some, the idea of a planned, painless birth is a dream come true.

On the baby front, C-section supporters claim that the health complications for babies born by elective C-section are rare and usually treatable. Babies born via C-section do look a bit different than babies born through the vaginal canal (their heads don’t get squished), but after a few days they all look the same. However, while C-section advocates may be correct that severe birth complications, such as a stillbirth, are very rare in elective C-sections, we are now learning that there are significant health concerns associated with C-sections, including an increased risk of chronic disorders later in life, such as asthma, allergies, obesity, autism, IBD, and celiac disease. The elevated rates of these issues associated with C-sections hover around 20 percent for most of them. This is tremendously worrisome, considering that many countries have a C-section rate well above what the WHO recommends. Approximately 6.2 million unnecessary C-sections are performed around the world, with Brazil, China, the United States, Mexico, and Iran accounting for 75 percent of them. Brazil and China have an outright C-section epidemic; many hospitals in those countries deliver more than 85 percent of their babies surgically. The situation in Brazil has reached critical levels, as many women there have to give birth by C-section without the medical need for it, simply because of the shortage of hospital beds allotted for vaginal deliveries (see Brazilians Love C-sections, page 69).

The good news (kind of) is that it isn’t the procedure itself that causes these disorders. Rather, it’s something extremely important that does not occur during the few minutes it takes for a doctor to surgically remove a baby from the womb: the baby does not come in contact with his mother’s microbe-rich vagina and feces.

A Dirty Birth Is a Good Birth

A baby’s very first encounter with microbes most likely happens when his head comes out through his mother’s vagina. As previously mentioned, the vagina contains an extremely high number of microbes, so the seconds (or minutes) it takes for a child to exit the birth canal are enough to impregnate a newborn’s mouth, nose, eyes, and skin with many of them. It’s also very common for women to defecate during birth, especially during the pushing stage. Babies usually exit the birth canal with their mouths facing their mom’s anus, and it is now proposed that this position allows for additional exposure to maternal fecal microbes.

It makes total sense. The world is full of microbes, and all babies are going to get soaked with them immediately after birth, regardless of how they are born. Why not make sure that a baby gets coated in the microbes from which she will benefit most? Nature sees to it that the type of microbes first encountered by babies born vaginally are the ones that are going to aid in the digestion of milk, as well as contribute to the development of a baby’s immature immune system, and even protect them against infections. Vaginal secretions are packed with Lactobacillus, whereas another milk-digesting bacteria known as Bifidobacterium come from feces. You’ve probably heard these two types of bacteria mentioned in yogurt advertisements. It’s no coincidence that these bacteria are used in the dairy industry, as they’re experts at digesting or fermenting milk and are also associated with health benefits. Unknowingly, every mother seeds her baby with a special custom package of microbes that will best suit her baby’s needs. Babies instinctively seek their mother’s breast shortly after birth, and breast milk is exactly what these microbes need to flourish in the baby’s gut. This wonderful synchrony of biological events is a fine lesson in how nature works.

However, not every birth ensures the passage of beneficial microbes to newborns. As discussed in chapter 3, if the vaginal microbiota is unbalanced (low amounts of Lactobacilli in vaginal secretions), or if a woman has tested positive for Group B streptococcus (GBS), a baby will not get the same kind of microbial bath from her mom. Given how important it is to receive those beneficial microbes at birth, it’s critical that women pay special attention to their vaginal microbiota in the weeks preceding birth. If there are any signs of a vaginal infection (itchiness, burning sensation during urination, or abnormal discharge), it’s recommended that the mother consult a doctor and follow treatment with oral and vaginal probiotics as appropriate. In fact, given the proven safety of probiotics during pregnancy, all expectant mothers should consider including probiotics in their diet, especially in the weeks preceding birth (see additional recommendations in chapter 3).

If one could view birth through a microscope, a C-section is drastically different than a vaginal delivery: their microbiota is remarkably dissimilar. Studies comparing the gut microbiota of newborns in the days and weeks following birth consistently show that babies born by C-section have lower numbers of Lactobacillus and Bifidobacterium, as well as divergences in several other bacteria. These babies are colonized by microbes often found on skin, soil, and other external surfaces, instead of vaginal and fecal microbes. Even more worrisome, some of these differences persist and can still be detected when children are seven years old, according to a 2014 Dutch study.

To better understand how different a C-section is in the context of microbes, lets trace a baby’s possible route of microbial exposure following a C-section. The brand-new bundle of joy goes from the doctor’s sterile gloved hands to a table or a scale where he’s touched with medical utensils and cloths. He may also brush someone’s lab coat or hand in the process. If all is well, minutes later the baby is brought to his parents, and they can finally touch and kiss him, providing skin and mouth contact. Very often the baby is not allowed to breastfeed until his mother has started to recover from the anesthesia, which takes hours in most cases (although a few hospitals are now allowing this right after delivery). During this period, the baby will likely be wiped clean, warmly bundled in a clean hospital blanket, and placed in a cot, heated by a lamp, where he is offered warm (sterile) formula. During all this, the baby is exposed to the air, which has many microbes, but they are very different from mom’s microbes, the ones humans are adapted to get exposed to at birth. It can take up to two hours before the baby is returned to his mother, when he can finally try breastfeeding for the first time.

Seeding Hope for the Future

Clearly, a baby born via C-section surely misses out on something crucial: that first splash of mom’s microbes. But rather than judging mothers who have decided to give birth this way, whether by choice or due to medical necessity, we need to look at what can be done to make C-sections a more microbiota-friendly choice.

How can one restore a baby’s microbiota following a C-section? If you think about it, the way vaginally born babies are exposed to microbes is very simple: they come in contact with vaginal secretions. Why not inoculate a baby born by C-section with mom’s vaginal secretions shortly after birth? Such procedures, called “seeding,” are currently being used and tested in several hospitals around the world, and have been gaining an increasing amount of attention.

Veronica, a thirty-three-year-old mom from Edmonton, Canada, had to schedule a C-section some weeks prior to her due date because her baby was in breech position. However, she was aware of the importance of imparting her microbiota to her baby during vaginal birth and decided to talk to her midwife about this. Her midwife came up with a plan. She inserted a piece of sterile gauze into Veronica’s vagina while she was waiting to be taken to the operating room. Minutes before her C-section, her midwife removed the gauze and placed it in a sterile glass container. Right after their baby girl was born, Veronica’s husband took the gauze with gloved hands and swabbed it inside the baby’s mouth and on her skin. Veronica also swabbed her own nipples, with the hope that the infant would take in even more vaginal microbes while breastfeeding.

As far-fetched as this method may sound, Veronica is part of a growing trend of moms and health practitioners who are trying it. Not only does it make scientific sense, but there’s also scientific evidence backing up its effectiveness. Dr. Maria Dominguez-Bello, a scientist at NYU and a leading expert in the field of microbiota studies, has focused her attention on the development of early microbiota. She recently conducted a study involving eighteen births, in which babies born by C-section were “seeded” with mom’s vaginal secretions and placed on mom’s chest. Her team found that this process resulted in the microbiota of “seeded” babies becoming much more similar to that of a baby born vaginally. “While not equivalent to a baby born vaginally, there is some important restoration happening,” she says. It’s still unknown whether this simple procedure will reduce a baby’s risk of suffering a chronic illness later in life. Her research group will follow up with these children in the years to come. Additionally, her group is working on conducting a much larger study that can provide sufficient evidence in terms of the safety of this practice. In the meantime, there’s a compelling argument that women planning to have a C-section should discuss this option with their doctor or midwife.

Antibiotics During Birth

Antibiotics are routinely administered in conjunction with a C-section, given intravenously as a precaution against infection. As one can imagine, with the surge in C-sections, there has been a similar increase in the use of antibiotics during birth. In this instance, the antibiotics are truly necessary, as 10–15 percent of women that undergo C-sections will develop an infection. But it’s up for debate whether the antibiotics have to be administered before surgery, or if it can wait until after the baby has been delivered. If given before the C-section, the baby will likely be exposed to the antibiotics, further compromising her microbiota at birth. If given after, the mother will still get the treatment she needs to prevent an infection and the baby will not be directly exposed to the antibiotic.

This was the case for Carley, now the mom of a healthy three-month-old daughter. During a doctor visit early in her third trimester, Carley learned she would have to deliver her baby via C-section (an umbilical cord abnormality made a vaginal birth too risky). As a naturopathic doctor herself, Carley had hoped for a vaginal birth, but she was aware of the need for a C-section for the safety of both her and her baby in this case. At the same time, Carley was aware that C-section babies have an increased risk of developing allergies, asthma, and obesity, with current research showing that a difference in microbial exposure influenced this risk. She had been taking daily probiotics throughout her pregnancy, but knowing that she would receive antibiotics before her birth, she was concerned that her baby would not received the optimal amount and type of microbes during birth. Carley explained her concerns to her obstetrician, who agreed to administer the antibiotics after her baby was born. They also agreed to “seed” her baby with her vaginal secretions after birth. Carley’s C-section went smoothly and she recovered very well from it. She continued to take probiotics and to eat a healthy and varied diet to help restore her microbiota afterwards.

As in Carley’s case, doctors are getting an increasing number of requests to administer antibiotics to the mother only after the baby is delivered, and even to forego antibiotic treatment altogether. While delaying the administration of antibiotics is a reasonable proposition, eliminating antibiotics during a major surgical procedure puts the mother at a very significant risk of infection. Like all medical decisions, the risks must not outweigh a patient’s benefits. In this case, the desire to protect the mother’s microbiota is outweighed by the increased risk of a severe infection acquired during surgery.

Another common use of antibiotics at birth is the application of antibiotic ointment (erythromycin) in the eyes of newborns. This is routine in the US and Canada, aimed at preventing the development of eye infections from the bacteria that cause gonorrhea and blindness caused by chlamydia. Because the possible outcome of these infections in a newborn is so severe, it is a medical indication in all births, although countries such as Australia, the UK, Norway, and Sweden forego the practice. In the US, thirty-two states are required by law to administer this treatment, regardless of whether the mother has chlamydia or gonorrhea, or whether the baby was born vaginally or via C-section (the infection can occur only during a vaginal birth). Recently, the Canadian Paediatric Society stopped recommending routine eye prophylaxis; however, this has not yet filtered down to common practice and many children still receive this treatment.