BABIES IN DANGER
Babies born low in weight are at risk not only for perinatal morbidity and mortality but also long-term sequelae
By Dr. Sheila R. Alcantara
In a nation of 80 million people, four babies are born every minute. That's about 5,000 a day, 170,000 a month, and almost two million a year. Not all, however, are lucky to be born healthy. In a developing country like ours, 17 out of 1,000 babies born live succumb to various illnesses, whether present in utero, during birth, or after. And for the past several years, not much has changed.
A great number of these high-risk babies are diminutive creatures born with less body mass than their normal counterparts. These tiny and frail newborns struggle outside the protective mantle of their mother's womb, and battle against all sorts of external insults wrought by the outside world. It is a tough way to begin life.
Low, Very Low, and Extremely Low
Babies born too small are classified according to certain thresholds of birth weight. By definition, the World Health Organization, since 1950, has adopted 2,500 grams as the limit for low-birth-weight (LBW) babies. Those who tip below the scale even further are classified into very low (less than 1,500 grams) and extremely low birth weight (less than 1,000 grams).
The problem, of course, is not just the size. Many of these babies are also born too soon. Hence, LBW babies can either be preterm (born less than 37 weeks old), or term but with restricted growth, or preterm with restricted growth. Either way, such conditions are associated with increased neonatal illness and mortality. In fact, death during the first month of life is 40 times more likely among LBW infants, and skyrockets to 200 times the normal risk for those with very low birth weight.
It's a Big World Out There
Worldwide, over 250 million babies are born with low birth weight each year, comprising 17 percent of total live births. Nine out of 10 come from developing countries. In the US, LBW babies make up about seven percent of all live births, a figure that has remained fairly constant for the past 30 years. The highest rates are reported in Asia, where in the Indian subcontinent, one out of three babies is born low in weight. In Africa, rates range from five to 20 percent.
Generally, most LBW babies in developing countries are associated with growth restriction while still in the mother's womb. Preterm births account for the majority of LBW babies in the developed world.
The economic costs for the care of these small infants are tremendous. LBW babies stay at the neonatal intensive care unit for months and require constant care and attention. This amounts to a financial cost of about US$5 billion per year, nearly half of which is spent on the tiniest babies. The greater picture shows an even heavier burden in terms of long-term disabilities and risk for serious illness later in life.
Healthy Mothers Mean Healthy Babies
The unborn child is totally dependent on the mother for all its needs-from blood supply to nutrition, even exchange of waste materials has to be coursed through the vessels that connect the fetal circulation to that of the mother. It is not surprising then that the fetus is very much exposed to the maternal body milieu, and coupled with its immature defenses, making them particularly vulnerable to domestic and external insults.
Hence, myriad factors have been implicated in contributing to low birth weight. Even across diverse cultural groups, certain risk factors have been constantly shown to increase the likelihood of producing small babies. Most of the time, however, the likely culprit cannot be ascertained, and low birth weight may occur even with carefully planned pregnancies.
Maternal Risk Factors
Often, it is difficult to separate the risk factors between prematurity and term low birth weight. Generally, however, term births with intrauterine growth restriction (IUGR) are associated with conditions that interfere with the placental circulation, the growth of the fetus and general maternal health and nutrition. In contrast, infants born premature, whether weighing low or appropriate for gestational age, are associated with medical conditions that make it unsuitable for the baby to stay in the womb. Such conditions are detrimental not only to the baby but also to the mother.
Demographic Factors
Several studies have shown increased risk for LBW in very young (<17 years old) and older (>34 years old) mothers. In terms of race and ethnicity, blacks have been consistently shown to have twice the risk of LBW than whites. Rates among Asians, Native Americans, and Mexican Americans, though, are not much different from those among Caucasians. Meanwhile, there is a consensus that low socioeconomic status, especially in terms of level of parental education, is an independent risk factor for low birth weight.
Toxin Exposure
Cigarette smoking is undoubtedly a well-established risk factor for low birth weight, with a number of studies considering it the clearest risk factor. Babies of smokers have in fact a 2.4-fold-increased risk of being born low in weight compared with babies of nonsmokers. In addition, heavy alcohol drinking has also been shown to cause IUGR, while the association between illicit drug use, especially cocaine, is similarly strong.
Pregnancy Risk Factors
Epidemiologic studies have shown that mothers who are short and underweight are at higher risk for low birth weight. Moreover, first-time mothers have a 23-percent greater risk for delivering a growth-restricted infant, compared with those who have already previously given birth. Women with a history of one or more LBW deliveries also place them at 2.75-fold-increased risk than those who have none. On the other hand, several studies have shown that mothers who have inadequate weight gain during pregnancy are also more likely to give birth to LBW babies. More importantly, there is a great deal of evidence indicating that women who receive prenatal care, especially early in pregnancy, have lesser chances of giving birth to babies low in weight.
Medical Conditions
The one most important medical risk factor clearly associated with IUGR is hypertension. (See What Bothers Mother, page 14.) One study even shows a two- to four-fold increased risk for women with preexisting high systolic blood pressure. Its mechanism is related to consequent reductions of blood flow to the baby, which then causes decreased supply of nutrients and oxygen, leading to slowing of growth. Meanwhile, severe anemia is likewise implicated, as do congenital anomalies of the fetus and excessive vomiting during pregnancy (hyperemesis).
Certain infections can also lead to term but small babies. For example, infections collectively known as TORCH (toxoplasmosis, other agents, rubella, cytomegalovirus, herpes simplex), when acquired during pregnancy, can lead to small babies with congenital syndromes. Urinary and respiratory infections also produce bacterial products that may induce premature contractions of the uterus, leading to preterm labor and delivery.
There are also cases where the placenta may be partially or totally blocking the opening of the uterus (placenta previa or abruptio placenta), which may later lead to uncontrollable bleeding, and sometimes death, if the baby is not delivered as soon as possible. Finally, the rising number of multiple pregnancies, most especially noted in developed countries where assisted reproduction is becoming quite common, has contributed greatly to the number of LBW babies in recent years.
Complications and Long-term Outcome
Early in life, LBW infants struggle for survival. Not only are they at increased risk for serious disease and even death early at birth, these babies may also suffer from severe complications later in life. Although some authors note that a large majority of low birth babies are normal and healthy, as a group however, they have higher incidence of subnormal growth, adverse health conditions and developmental problems, the extent and severity of which increase as the birth weight decreases. Additionally, babies who are also born too soon are at risk for problems associated with the immaturity of their organ systems, including respiratory distress, brain damage, and heart, blood and metabolic disorders.
Furthermore, the smaller and more immature these babies are, the greater is their risk for neurologic and intellectual impairment. In fact, half of all babies weighing only 500 to 750 grams suffer from some form of blindness, deafness, mental retardation, or cerebral palsy.
At school age, babies who were born low in weight may also suffer from learning disabilities, attention disorders, and even breathing illnesses such as asthma. These problems may continue on until adolescence and even during adulthood. For instance, recent reports indicate that LBW babies are more likely to have high blood pressures as well as cardiovascular and other disorders in later life. It should be emphasized however, that not all of these adverse sequelae are completely irreversible, and are therefore amenable to medical treatment, as well as psychological and educational support.
Local Experience
Low birth weight is no doubt a significant public health problem that needs to be urgently addressed. But to institute effective preventive, control, and management strategies, an extensive evaluation of its scope and severity needs to be carried out. Unfortunately, the Philippines to date does not have a comprehensive registry that monitors the status of babies being born in the country. Because of this, the Philippine Pediatric Society is really pushing for the establishment of a common database for all hospitals nationwide, reveals Dr. Pura Flor Isleta, chair of the section of neonatal medicine at the University of the Philippines-Philippine General Hospital (UP-PGH).
Available data, however, show that 38 percent of all babies delivered at the PGH alone in 2000 weighed less than 2,500 grams. This went down to 24 percent in 2001. On a more optimistic front, the Philippine Children's Medical Center (PCMC)reports increasing survival rates of extremely low-birth-weight babies from 40 percent in 2000 to 66 percent in 2002. Other private hospitals taking care of extremely low-birth-weight infants recorded mortality rates ranging from 38 to 66 percent between the 2000 and 2002 (data from Dr. Carina Cruz, PCMC).
Isleta further notes that among Filipino women, the most frequently encountered maternal condition associated with low birth weight is high blood pressure, particularly preeclampsia, a form of hypertension in pregnant women that severely compromises uteroplacental circulation. In women who undergo preterm deliveries, placenta previa is also quite common.
Prevention Is Still the Key
Despite the enormous advances in the care of high-risk small babies, much still needs to be known in terms of distinctive etiologies and risk factors for low birth weight, whether in growth-restricted or premature babies. The costs are high not just in terms of risks for impairment of the quality of life of these individuals and the psychological effects on them and their families, but also in terms of financial burden in the treatment and care of these patients. Preventive efforts to address intrauterine growth restriction and premature birth make a very viable and practicable strategy that must be rigorously pursued.
Logically, prevention must be aimed at minimizing, if not eradicating, associated risk factors for low birth weight. In studies abroad, it has been shown that smoking is the single largest modifiable risk factor for low birth weight and infant mortality. In some countries, it accounts for up to 20 percent of LBW cases. On the other hand, the strong association between socioeconomic status and low birth weight has pushed some governments into establishing social welfare programs aimed at reducing poverty and its devastating effects. Greater prenatal care coverage of women, especially where such programs target known causes of low birth weight, is also expected to bring down LBW rates. Meanwhile, a recent study by the Johns Hopkins Bloomberg School of Public Health showed that folic acid-iron supplement lowers LBW risk by as much as 16 percent.
For Isleta, the best way to prevent babies from being born low in weight is good prenatal care. Says the foremost neonatologist: "We have shown that women who receive prenatal care, especially those seen at our high-risk clinic, have better outcome than those who come in imminent delivery." She advises women to consult a doctor once they know that they're pregnant. Education also comprises a very important component of prenatal check-ups, and mothers must be informed of probable risk factors and ways to correct them.
On the hospital level, Isleta notes that because of patient overcrowding in government hospitals like the PGH, the quality of care being given these babies is compromised. Consequently, she advocates bringing health care to the regional level by assigning hospital catchment areas that will be made responsible for high-risk babies. This will allow for babies who require special treatment to be distributed among different centers. This strategy is being practiced in other countries such as the US, and current indirect evidence indicates a sharp decrease in infant deaths after adoption of a regional setup.
What Next?
The well-being of a nation's women and children are a reflection of the adequacy of its health-care system. While the US reports almost 100-percent coverage of some form of prenatal care among, the Philippines is witness to mothers giving birth without ever having seen a doctor during their entire pregnancy, or not once having taken iron supplements, much less having an ultrasound done at any time of the long nine months of gestation. Of course, our state of health is just a microcosm of the even greater problems besetting our country, all of which are interlinked. The birth of a single child must not be viewed as another problem that needs to be solved, but as a promise that sows the hopeful seed that produces the great people of this nation. As the foremost Filipino hero once said, the youth is the hope of the nation. It is therefore one's duty to ensure their bright future.
There lies the challenge.
|
