WHAT’S YOUR PELVIC SHAPE?
Whatever the shape of your pelvic bones, they’re important to your postreproductive health. They can impact childbirth’s physical ease or difficulty, the way your baby travels through the birth canal, and the amount of pressure, stretch, and potential injury to each area along the way. That, in turn, has an impact on the problems you’re at risk for afterward.
Consider the shape of your pubic arch, formed by the bones that you can feel for yourself at the front of your pelvis, below your pubic hairline. If the pubic arch is narrow (android or anthropoid), that means less room for the fetus in the front of your pelvis. As a result, a large fetal head or wide shoulders may be more likely to stretch and tear downward, into the perineum and rectum, during delivery. If, on the other hand, you have a wide pubic arch (gynecoid, platypelloid), or a tailbone that angles forward, the fetal head might tend to be pushed up toward the pubic bone, directly into the bladder and urethra. What if the bones are narrow along the sides of your pelvis, creating pressure points between the fetal head and the pudendal nerve running along each pelvic side wall? Consider how much more force might be applied to those nerves in a narrow anthropoid pelvis, compared with a wide gynecoid one.
A great deal remains to be learned about how pelvic shape may influence the effects of vaginal delivery on your postreproductive body. In chapter 4, you’ll learn how your doctor or midwife might evaluate your pelvic shape during a pelvic examination.
Physical Challenges: Your Pelvis During Pregnancy and Delivery
PREPARING AND ADAPTING: BABY AND MOM
Nobody ever said that life would be easy or worry-free. But could there be any match for the emotional stress a fetus might feel, lying in the womb the night before beginning its journey through the pelvis? Our in utero friends face a struggle of epic proportion on their way out—the equivalent of a slow train ride through a tunnel that’s narrower than the train itself. But fetuses are equipped with several remarkable features that ease their journey, including soft spots between skull bones that actually bend and overlap (molding), naturally lubricated skin, and that well-known cone-head shape that narrows the width of the baby’s cranium. Like a good Boy Scout or Brownie, a fetus arrives in the labor room prepared.
The pelvic organs and pelvic floor during pregnancy
The changes that occur within Mom’s pelvis are equally impressive. Throughout the nine months of pregnancy, the lower half of your body takes a number of steps in an effort to prepare itself for the big task ahead.
First, changes occur to the soft tissues of your pelvis. The vaginal walls become significantly thicker as the stretchy smooth muscle enlarges and the usually firm connective tissue layer softens. While these changes cause the vagina to become longer and thicker, there is also a steady increase in vaginal secretions and natural lubrication, which enables your soft tissues to stretch out of the way. Perhaps more surprising are the changes taking place with your pelvic bones. A special hormone produced by the ovary during pregnancy, appropriately named relaxin, appears to cause relaxation and some expansion at the pelvic joints. The pubic symphysis, which is the connective tissue connecting the bones right at the front of your pelvis, becomes mobile and wider—these pubic bones can separate (diastasis) up to several centimeters in some women! Also, the sacroiliac joint, connecting the side bones of your pelvis to your lower spine, becomes more mobile. When your hormone levels return to normal after birth, the pelvic bones return to their original rigid state. But as your body anticipates the evolutionary mismatch of a lifetime, these changes are taking place to reduce your odds of physical harm.
YOUR DUE DATE ARRIVES—ARE YOU ENGAGED?
“Has the head dropped yet?” It’s a question asked by many women during their last month or two of pregnancy. But what does this question actually mean? As your due date nears, the baby’s head often lowers itself into the bony pelvis. When the widest part of the fetal head secures itself within the pelvic cavity, the fetus has become engaged, in obstetrical terms. Some women may suddenly feel they’re able to breathe more easily, since they’ve begun to carry lower. Others notice increased urinary frequency and constipation as the fetal head creates more pressure in the pelvis. Engagement does not always occur before your first labor begins; one recent study conducted by midwives found engagement in only 31 percent of first-time mothers-to-be, though most other estimates have been higher. Nevertheless, when engagement does occur in a first pregnancy, many practitioners consider it a sign that a good fit exists between mother and baby, perhaps reflecting an easier labor and delivery ahead. In subsequent pregnancies, when the pelvic tissues are more lax, an unengaged fetus at the onset of labor is not considered a prognostic sign.
But what if you’re past the due date of your first pregnancy and the baby’s head is still floating up above the pelvic bones, unengaged? According to some obstetricians, this might represent the first warning that your pelvic shape and your baby’s head aren’t the world’s most ideal fit; there is data to show that you might be at higher risk for a labor that fails to progress to a successful vaginal delivery. One recent Johns Hopkins study of more than twelve hundred women carrying their first pregnancy showed the risk of cesarean section nearly tripled if the baby’s head was not engaged when active labor began. Another study found that a floating fetal head conferred a longer second stage of labor (the time from being fully dilated until delivery) and increased the risk of cesarean from 6.9 to 27 percent. Other studies have contradicted these findings, concluding that engagement might not be a very reliable predictor of a successful vaginal birth. Many practitioners disregard the issue of engagement, claiming equal success at achieving vaginal delivery even if the fetal head is floating.
What does all this have to do with your pelvic floor and postreproductive body? It’s a matter of what efforts are required to achieve vaginal delivery and how these efforts might impact your body. Delivery of an unengaged fetus might take considerable extra effort and reduce your odds of an easy vaginal birth. But deciding whether this extra time and effort creates more risk of physical injury to you is not usually clear. Engagement is just one measure of maternal-pelvic fit, which has prognostic value only during your first pregnancy and can’t flawlessly forecast an easy versus a traumatic delivery. The significance of fetal engagement remains a question that future research will hopefully help to resolve.
LABOR—THE PELVIS UNDER PRESSURE
Finally, labor begins. Obstetricians and midwives divide labor and delivery into a few stages, and acquainting yourself with them can help you to understand how childbirth might affect your body.
Labor’s first stage begins when your uterine contractions become painful and frequent, and the cervix begins to dilate—that is, to open. It ends when the cervix is fully dilated at ten centimeters. The first stage of labor requires patience—during your first pregnancy, reaching just four to five centimeters can take up to twenty hours from the time your labor contractions first begin. Most women remain at home during the early part of this stage; after arriving at the maternity unit, some may rest with the help of pain medication, while others walk the hallways or even lie in a warm bath. But however they’re laboring, most are focused on one central question: “Am I ten centimeters yet?”
When you do reach ten centimeters—or, more precisely, when the cervix is fully dilated—you’ve entered the second stage of labor. This stage ends with delivery of your infant. Its duration ranges from around two hours for a first delivery to only twenty minutes for women who have had previous vaginal births.
When the second stage begins, one of the first things you’ll notice is more intensive monitoring by the doctors and nurses of both your labor progress and your baby’s well-being. The beginning of the second stage is usually when you’re instructed to start pushing, the most physically stressful part of labor for both baby and mom. Fully dilated might accurately describe the cervix as the second stage begins, but it’s not true for the rest of your pelvis.
A tremendous amount of dilation throughout the pelvis has yet to occur, and the majority of fetal descent still lies ahead. Along the way, as this dilation and descent take place, stretch and compression affect the vagina, bladder, urethra, muscles, and nerves. When you push, all of these forces are magnified. Pressures generated between the fetal head and vaginal wall can average 100mmHg and reach peaks of 230mmHg. For those of you without an engineering or physics background, rest assured that this a remarkable force in biological terms. A force of only 20 to 80mmHg will stop the flow of blood in most human tissues, and can damage them beyond repair if applied for a prolonged period. As you can imagine, forces up to three times that intensity, within the narrow confines of the pelvis, might change nearby structures.
Aim your telescope at childbirth drama during labor’s second stage, and you’ll observe a true irony within modern women’s health care: a monitored fetus and a sometimes overlooked mom. You’ll see most eyes in the modern delivery suite—including those of the health-care team, the mother, and her partner—trained on the squiggly lines of the fetal monitor from the start of the pushing, squatting, and “hut-hut-hooing” to the baby’s first cry. All the while, the maternal pelvic changes, which can affect some women for a lifetime, may escape the gaze of all the players on childbirth’s stage.
Arguably, the potential effects of labor on the maternal body are among the most neglected topics in women’s health. In chapters 4 through 7, you’ll learn about the ways you can help yourself—through prenatal preparation, pushing techniques, avoidance of risky procedures, and so on—making it less an event of chance and more a process of choice.
MAKE YOURSELF A REAL MAGICIAN
Childbirth is a magical experience for women and their partners. Unfortunately, doctors and midwives are not magicians! Guiding a baby through your pelvis is far trickier than pulling a rabbit out of a hat, and the problems that you can be left with are not entertaining. Once you understand your postreproductive body, you’re on track to improving your heath, relieving your symptoms, and possibly even preventing future ones. Knowledge works like real magic, and the upcoming chapters will provide you with countless tricks of the trade.
NEW PERSPECTIVES ON YOUR POSTREPRODUCTIVE BODY
You’ve become aware of the pelvic floor, an important area of your body that you may not have known before. You’ve learned that it looks a certain way before childbirth and another way afterward. With this new “pelvic perspective” in mind, let’s examine how various obstetrical events and procedures can affect your function afterward, and what to do when things go awry.
The Pelvic Floor After Childbirth
INJURIES AND ANATOMIC CHANGES AND THE OBSTETRICAL EVENTS THAT CAN CAUSE THEM
Between the oceans of pain, there stretched continents of fear; fear of death and dread of suffering beyond bearing.
—Woman, 1885, on childbirth
Can I get my epidural, please?
—Woman, circa 1995, on childbirth
Whether childbirth is easy or difficult, long or short, natural or operative, one fact remains constant: a woman’s body will never be exactly the same after pregnancy, labor, and delivery, as it was beforehand. The good news? For the vast majority of women, these physical changes are subtle and inconsequential, visible to the doctor during a pelvic exam but creating no problems for the woman herself. The other side of the story? If you’ve reached for this book, it’s likely that you have noticed some sort of change, and you’re looking for relief. As the next step, now that you’re familiar with your pelvic area, it’s time to learn about the most common and significant changes that can arise.
Perineal Injuries and Episiotomies
Dr. David Chapin, an esteemed vaginal surgeon at Harvard Medical School, has been known to occasionally quip to the resident physicians he’s instructing: “The obstetrician-gynecologist spends the first half of his career supporting the perineum, and the second half of his career being supported by the perineum.” Dr. Chapin makes this point with a lighthearted touch, but it has stuck in my mind and always rings true. The same women who keep young obstetricians busy in the labor suite tend to keep them busy again in the operating room years later, reconstructing those pelvic supports that were lost during childbirth. For countless women, the specialty called obstetrics and gynecology could be more accurately dubbed obstetrics, therefore gynecology.
YOUR PERINEUM DURING AND AFTER CHILDBIRTH
During childbirth, as the fetal head or shoulders are delivered, the perineum can tear spontaneously or be cut intentionally with an episiotomy. Perineal tears can be partial, extending only through the vaginal skin; or they can be complete, extending all the way through the perineal muscles and even into the rectum. If the perineum is torn during childbirth and not adequately repaired, any or all of the perineal muscles (including the bulbocavernosus and transverse perineal) can become permanently separated, creating a gaping appearance to the vaginal opening.
When childbirth widens the perineum, you may later begin to notice a bulging sensation near the vagina and rectum, or a loss of sensation or vaginal fullness during intercourse. When the anal area is involved, it can lead to incontinence of both gas and stool. If, on the other hand, the perineum becomes too tight or scarred, intercourse may be painful. Even with a proper repair, the perineal muscles and tissues may not properly heal. In chapter 7, you’ll learn more about alleviating the problems that can accompany healing of your perineum. You’ll also learn how to help prevent these injuries from occurring in the first place.
DID YOU KNOW …?
Even in the absence of an episiotomy, between 35 and 75 percent of women suffer some degree of perineal injury while giving birth. For those who have a perineal injury during their first delivery, the risk of a spontaneous perineal tear during the next delivery is more than tripled.
(Above) Perineal anatomy before delivery. (Below) Common changes after childbirth, affecting the perineum and nearby structures
EPISIOTOMY: THE “LITTLE CUT”
For some women, the decision over episiotomy—to cut or not to cut—symbolizes whether her delivery is smooth or traumatic, natural or medicalized, and whether she considers herself injured or intact afterward. The procedure is performed with a snip of the perineum, that bridge of tissue between the vaginal and anal openings. By creating more space at the vaginal opening, episiotomies hasten delivery of the newborn. Did you know that aside from cutting the umbilical cord, episiotomies are the most common obstetrical operations (1.2 million per year) performed in our country and also across the world?
First utilized in Europe, episiotomies were imported to the United States and brought into widespread use during the early 1900s. For decades thereafter, many doctors performed them routinely, claiming they resulted in a wide variety of benefits: speeding labor, protecting pelvic muscle tone, preserving sexual function, aiding maternal healing, sparing compression of the fetal head, and reducing the risk of anal sphincter injury. To this day, some practitioners argue that it’s better to cut and neatly repair the perineum and vagina than to allow these tissues to spontaneously stretch and lose their virginal tone altogether.
But among the majority of physicians, there has been close to a 180-degree reversal in these beliefs. The strategy of routine episiotomy simply has not withstood the scrutiny of modern research, and it is no longer mainstream. At least five studies have shown that episiotomies seem not to protect against the development of urinary incontinence. In fact, there is plenty of evidence to suggest that episiotomies increase the overall risk of harm to your pelvic function.
INJURIES FROM EPISIOTOMIES: ANAL SPHINCTER, PELVIC MUSCLES, HEALING, AND PAIN
It’s unfortunate but perhaps not all that surprising how few high-quality research studies have been performed to understand the physical effects of episiotomy. After all, this procedure involves a highly intimate area of the female body charged with a rich supply of nerve endings, making it a complex area to study and master. Beyond that, episi
otomies have always been highly politicized—representing, for many women, a symbol of invasive delivery, and making physicians and patients equally reluctant to test different strategies at the time of birth. Despite the fact that our understanding of this procedure has evolved at a shamefully slow pace, a fairly clear picture has begun to emerge. It’s perhaps best summarized by the Cochrane Group, a team of analysts that draws scientific conclusions based on the best research for a given topic. Their report concluded that routine episiotomy increases the overall risk of trauma and complications during vaginal delivery, and therefore should be used selectively. But what are the specific benefits of avoiding episiotomy that led to this overarching conclusion?
To improve healing and preserve muscle strength. One study from several years ago involved more than two thousand Argentinean women who were randomly assigned to receive either routine episiotomy or selective episiotomy based on need—in other words, performed only if their obstetrician felt that a significant perineal injury was about to occur. Overall, pain and healing complications were found to be more common among women who received routine episiotomy. Other studies indicate that over the long term, women who undergo episiotomy tend to be left with weaker vaginal muscle strength than those with an intact perineum after delivery, or those who tear spontaneously. Eventually, this weakening of vaginal muscle might tip the balance of continence or pelvic support for a good number of women.
To spare lacerations. During first deliveries, episiotomies in general appear to increase the risk of a torn anal sphincter. Midline episiotomy (a straight-down incision from the opening of the vagina toward the anus) in particular has been associated with up to twenty times the usual risk of lacerations involving the rectum; one large Canadian study found that nearly all tears extending into the anal sphincter muscle followed an episiotomy. With second, third, or later deliveries, the overwhelming majority of severe perineal injuries originate with episiotomies. In Sweden, a decline in episiotomy rate from 28 to 10 percent was associated with a slightly decreased rate of anal sphincter injury.
Ever Since I Had My Baby Page 5