Having a baby is good for your bones
It prevents hip fractures later in life.
"TUESDAY, April 22 (HealthScoutNews) - Having a baby is good for your health - or
at least the health of your bones, says a new study of nearly 10,000 women.
The research, published in the May issue of the Journal of Bone and Mineral Research,
found women who give birth to at least one child dramatically reduce their risk
of hip fracture later in life, compared with women who remain childless.
What's more, the greater the number of babies you have, the greater your protection.
"We don't expect this finding to alter a woman's thinking about her childbearing
options, but we do hope it will send an important message to women who do not plan
to have children to take steps beginning in their childbearing years to protect
their bones later in life," says Dr. Teresa Hillier, an endocrinologist and principal
investigator for the study at the Kaiser Permanente Center for Health Research in
Oregon.
The new study also found a bone mineral density test (BMD), an important measure
of bone strength, did not predict the fracture risk in the childless group.
"A bone mineral density test is a very important indicator of bone health, but clearly,
it does not tell the whole story, particularly in women who remain childless," Hillier
says.
Although the researchers can't say for sure why pregnancy has this protective effect,
Hillier theorizes it may slightly alter the shape of the bones, as well as strengthen
some support muscles in the hip, ultimately reducing the risk of hip fracture.
Endocrinologist and osteoporosis specialist Dr. Loren Wissner-Greene calls the study
intriguing, and sees several more possibilities for the findings.
"Even though the bone density is the same in both groups of women, it's possible
that pregnancy may alter the micro architecture of the bone - affecting the inner
structure in a way that makes it stronger in certain areas of the body," says Wissner-Greene,
a professor of endocrinology at New York University Medical Center.
In addition, she says, because weight-bearing exercises have been known to increase
bone strength, it's possible the extra weight of pregnancy may help build stronger
bones, particularly in the pelvic region.
The new research involved nearly 10,000 postmenopausal women aged 65 and older who
were enrolled in the multi-center, U.S. government-funded Study of Osteoporotic
Fractures - the largest long-term observation study of its kind.
The women were divided into two groups - those who had given birth to one or more
child, and those who remained childless. The researchers measured bone density at
the wrist, hip and spine, and questioned the women on a variety of health and lifestyle
factors. These included their age at the time of their first and last menstrual
periods, height and non-pregnant weight at age 25, change in weight since age 25,
and calcium intake from ages 12 to 18 and ages 18 to 50.
In addition, the researchers also noted the women's level of physical activity before
and after age 25, family history of fractures, whether or not they smoked, their
personal exercise history, and the number of hours they spent each day sitting or
lying down - all factors that could influence bone health. The researchers also
documented any personal history of hyperthyroidism, diabetes, hysterectomy or oophorectomy
(ovary removal), as well as all regular use of medications, including hormone replacement
therapy.
History of bone fracture before the start of the study was documented, while regular
follow-ups during the study period provided continuing updates on fracture risks.
After adjustments were made for all lifestyle factors, the researchers found women
who had one or more babies were 44 percent less likely to experience a hip fracture
than women who remained childless. Interestingly, the risk of spine and wrist fractures
remained the same in both groups of women, and all the women had similar levels
of bone density.
To further tease out the effects of childbearing, the researchers then divided the
group of mothers according to the number of children they had had. The result: The
greater the number of children, the lower the risk of hip fracture.
"The important message in this finding is that women need to pay attention to bone
health beginning in their childbearing years, and both women and their doctors need
to take a woman's childbearing history into account when planning preventative care
programs," Hillier says."