Premature birth

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Premature birth
Classification & external resources

ICD-10	O60.1
ICD-9	644
DiseasesDB	10589
MedlinePlus	001562
eMedicine	ped/1889

Contents 1 Overview 2 Factors 3 Prevention of preterm birth 4 Symptoms and indications 5 Maternal treatments 6 Newborn complications 7 Treatment measures for a premature infant 8 Prematurity and the parent 9 In popular culture 10 References 10.1 Notes 10.2 Bibliography 11 See also 12 External links

[edit] Overview

Premature birth (also known as preterm birth) is defined medically as childbirth occurring earlier than 37 completed weeks of gestation. Most pregnancies last about 40 weeks. About 12 percent of babies in the United States — or 1 in 8 — are born prematurely each year. ^[1] In 2003, more than 490,000 babies in the U.S. were born prematurely. Worldwide rates of prematurity are more difficult to obtain as the lack of widespread professional obstetric care in developing regions makes determination of gestational age less reliable. The World Health Organization instead tracks rates of low birth weight, which occurred in 16.5 percent of births in less developed regions in 2000.^[2] It is estimated that one-third of these low birth weight deliveries is due to prematurity.

The shorter the term of pregnancy, the greater the risks of complications. Infants born prematurely have an increased risk of death in the first year of life (infant mortality), with most of that occurring in the first month of life (neonatal mortality). Worldwide, prematurity accounts for 10% of neonatal mortality, or around 500,000 deaths per year.^[3] In the U.S. where many of the infectious and other causes of neonatal death have been markedly reduced, prematurity is the leading cause of neonatal mortality at 25%.^[4] Prematurely born infants are also at greater risk for developing serious health problems such as: cerebral palsy, chronic lung disease, gastrointestinal problems, mental retardation, vision and hearing loss.^[5] It has also been shown that premature babies are prone to developing depression as teenagers. ^[6]

Although there are several known risk factors for prematurity (see below), nearly half of all premature births have no known cause. When conditions permit, doctors may attempt to stop premature labor, so that the pregnancy can have a chance to continue to full term, thereby increasing the baby's chances of health and survival. However, there is currently no reliable means to stop or prevent preterm labor in all cases. In fact, the rate of preterm births in the United States has actually increased 30% in the past two decades.^[7]

In developed countries premature infants are usually cared for in a special section of the hospital known as the NICU (Neonatal Intensive Care Unit). The physicians who specialize in the care of very sick or premature babies are known as neonatologists. In the NICU, babies are kept in incubators (also called isolettes), which are bassinets enclosed in plastic with climate control equipment designed to keep babies warm and limit their exposure to germs. Modern neonatal intensive care involves sophisticated measurement of temperature, respiration, cardiac function, oxygenation, and even brain activity. Treatments may include fluids and nutrition through intravenous catheters, oxygen supplementation, mechanical ventilation support, and medications. In developing countries where advanced equipment and even electricity may not be available or reliable, simple measures such as kangaroo care (skin to skin warming), encouraging breastfeeding, and basic infection control measures can significantly reduce preterm morbidity and mortality.

[edit] Factors

There are many known factors related to premature births. However, the nature of the relationship between these factors and premature births are unclear.

• A woman's previous history of preterm birth, or pregnancies that ended in miscarriage.
• Multiple pregnancies (twins, triplets, etc.) are at a higher risk for premature birth.
• Uterine or cervical abnormalities.
• Certain chronic disease such as high blood pressure, kidney disease and diabetes.
• Infections of the cervix, uterus or urinary tract. Certain STDs, Beta Strep.
• Substance abuse of tobacco, alcohol and other drugs.
• Women who have tried to conceive for more than a year before getting pregnant are at a higher risk for premature birth. A recent study done by Dr. Olga Basso of the University of Aarhus in Denmark and Dr. Donna Baird of the U.S. National Institute of Environmental Health Sciences suggests that women who had difficulty conceiving were about 40 percent higher risk of preterm birth than those who had conceived easily.
• Women under 18 or over 35 are at a higher risk for premature birth.
• Inadequate nutrition during pregnancy.
• Antepartum hemorrhage
• Pre-eclampsia
• Stress
• Periodontal disease

[edit] Prevention of preterm birth

Some newer research has identified possible methods to prevent preterm birth, pre-eclampsia/eclampsia, premature rupture of membranes, and preterm labor.

This research includes self-care methods to reduce infections, nutritional and psychological interventions, and the control of preterm birth risk factors (eg. working long hours while standing on feet, carbon monoxide exposure, domestic abuse, and other factors). Injection with a form of progesterone (17 alpha-hydroxyprogesterone caproate), taking fish oil supplements, and self-monitoring vaginal PH followed by yogurt treatment or Clindamycin treatment if the PH was too high all are effective at reducing the risk of preterm birth. ^{[8] [9]}

This research is quite new; however, doctors using these newer strategies have obtained preterm birth rates as low as 1 to 2%, compared to the 11 to 16% currently in the US.^{[citation needed]}

[edit] Symptoms and indications

The symptoms of an imminent premature birth include:

• Four or more uterine contractions in one hour, before 37 weeks' gestation.
• A watery discharge from the vagina which may indicate premature rupture of the membranes surrounding the baby.
• Pressure in the pelvis or the sensation that the baby has "dropped".
• Menstrual cramps or abdominal pain.
• Pain or rhythmic tightening in lower abdomen or back.
• Vaginal spotting or bleeding.

[edit] Maternal treatments

There are two tactics that can be used to deal with a potential premature birth: delay the arrival of birth as much as possible, or prepare the prospectively premature fetus for arrival. Both of these tactics may be used simultaneously.

Delaying the premature birth from occurring is typically the most favored option. This gives the fetus or fetuses as much time as possible to mature in the womb. There are a number of techniques that can be used to try to accomplish this. The first resort is usually complete bed rest. Maintaining a horizontal position reduces pressure on the cervix, which may allow it to stay lengthened longer, and avoiding unnecessary movement may reduce uterine irritation, which can lead to contractions. Likewise, proper nutrition and especially hydration are important: dehydration can lead to premature uterine contractions. In a hospital setting, a drug-free IV drip may be used to try to stop premature labor simply by improving the mother's hydration. Lastly, there are anti-contraction medications (tocolytics), such as ritodrine, fenoterol, nifedipine and atosiban.

Premature birth can not always be prevented. Severely premature infants may have underdeveloped lungs, because they are not yet producing their own surfactant. This can lead directly to Respiratory Distress Syndrome, also called hyaline membrane disease, in the neonate. To try to reduce the risk of this outcome, pregnant mothers are routinely administered at least one course of glucocorticoids, a steroid that easily passes the placental barrier and stimulates growth in the lungs of the fetus. Typical glucocorticoids that would be administered in this context are betamethasone or dexamethasone, often when the fetus has reached viability at 23 weeks. In cases where premature birth is imminent, a second "rescue" dose of steroids may be administered 12 to 24 hours before the anticipated birth. There is no research consensus on the efficacy and side-effects of a second dose of steroids, but the consequences of RDS are so severe that a second dose is often viewed as worth the risk.

[edit] Newborn complications

Infants born more than 3 weeks prior to 40 weeks show physical signs of their prematurity and may develop other problems as well. These include, but are not limited to, the following:

Neurologic

• Apnea of prematurity
• Hypoxic-ischemic encephalopathy (HIE)
• Intracranial hemorrhage
• Retinopathy of prematurity (ROP)
• Developmental disability

Cardiovascular

• Patent ductus arteriosus (PDA)

Respiratory

• Respiratory distress syndrome (RDS or IRDS)
• Chronic lung disease (previously called bronchopulmonary dysplasia or BPD)

Gastrointestinal / metabolic

• Hypoglycemia
• Feeding difficulties
• Rickets of prematurity
• Hypocalcemia
• Inguinal hernia
• Necrotizing enterocolitis (NEC)

Hematologic

• Anemia of prematurity
• Thrombocytopenia
• Hyperbilirubinemia (jaundice)

Infectious

• Sepsis
• Urinary tract infection ^[1]

The earliest gestational age at which the infant has at least a 50% chance of survival is referred to as the limit of viability^[2]. As NICU care has improved over the last 40 years, viability has reduced to approximately 24 weeks, although rare survivors have been documented as early as 21 weeks.[3] As risk of brain damage and developmental delay is significant at that threshold even if the infant survives, there are ethical controversies over the aggressiveness of the care rendered to such infants. The limit of viability has also become a factor in the abortion debate.

Some of the complications related to prematurity are not apparent until years after the birth. For example, children who were premature babies (especially if born less than 1500 grams) have a higher likelihood of having behavioral problems, delays in motor development, and difficulties in school than their peers who were healthy full term babies. More than their peers who were full term, people who were born prematurely need services provided by physical therapists, occupational therapists or speech therapists.

[edit] Treatment measures for a premature infant

The required care for premature infants differs greatly depending on the child's gestational age, birth weight, and overall maturity. Measures common among extremely premature infants include:

• Placing the infant in a warmer or isolette. Premature infants are easily susceptible to cold-stress or hypothermia and infection, and preventing these is a key priority.
• Infants under 32 weeks typically do not produce enough surfactant in their lungs to enable them to breathe on their own. In these cases, surfactant will be administered to assist them.
• In extremely premature infants, a breathing tube may be inserted in the infant's trachea, and a ventilator and supplemental oxygen may be used.
• Adequate nutrition, via a feeding tube or, in extremely premature infants, intravenously. If a feeding tube is used, expressed breast milk from the mother or a breastmilk bank can be used, which lowers the risk of infections such as necrotizing enterocolitis.

[edit] Prematurity and the parent

Adjustment after preterm birth for parents can be very difficult. The NICU setting is foreign and often intimidating and scary. Additionally, parents often have difficulty becoming involved in their child's care because of the NICU setting. This affects the parents transition into parenthood because they are unable to fulfill their expected roles. Furthermore, often premature birth is accompanied by a difficult NICU course and therefore parents are forced to confront difficult decisions about their child's care. Studies have shown that the transition to parenthood for parents of preterm infants follows a different and longer course than that of parents with term infants.

In a study by Jackson et al (2003)^[4] researchers found that both mothers and fathers travel a course from alienation to responsibility to confidence to familiarity in approximately the first 18 months of the child's life.

In a separate study by McHaffie^[5], researchers found that parents of very low birth weight infants (<1500g/3.3lbs) follow a similar but slightly different course, likely because their infants tend to be more in peril. Mothers travel from anticipatory grief to anxious waiting to positive anticipation while the infant is in the NICU. After discharge the mother travels from anxious adjustment to exhausted accommodation to confident caring, usually within the first three months following discharge.

[edit] In popular culture

• On the show Freak Show, one member of the Freak Squad is Primi the Premature Baby.
• On medical drama, House, M.D. in episode entitled Forever, Dr. Gregory House mocks his subordianate, Dr. Robert Chase, for working in the NICU, suggesting that he's only trying to expand his "make-out pool" to include preemies as well. Previously in the season, Chase had kissed an underaged girl at her request because she had terminal cancer {2.2 Autoposy'}.

[edit] References

[edit] Notes

1. ^ Martin JA, Hamilton BE, Sutton PD, Ventura SJ, Menacker F, Kirmeyer S. “Births: Final Data for 2004.” National Vital Statistics Reports, vol. 55, no 1. Hyattsville, Maryland: National Center for Health Statistics, 2006.
2. ^ http://www.who.int/research/en/
3. ^ Child Health Research Project Special Report. "Reducing Perinatal and Neonatal Mortality." Meeting Report, vol. 3, no 1. Baltimore, Maryland, May 10-12, 1999.
4. ^ Mathew TJ and MacDorman MF. "Infant Mortality Statistics from the 2003 Period Linked Birth/Infant Death Data Set." National Vital Statistics Reports, vol. 54, no 16. Hyattsville, Maryland: National Center for Health Statistics, 2006.
5. ^ March of Dimes. The Growing Problem of Prematurity. October 2006.
6. ^ The Age Depression Linked to Premature Birth. May 2004.
7. ^ Mayo Clinic. Premature Birth. 6 Nov 2006.
8. ^ Lamont RF and Jaggat AN. Emerging drug therapies for preventing spontaneous preterm labor and preterm birth. Expert Opin Investig Drugs. 2007 16:337-45. PMID 17302528
9. ^ Hoyme UB and Saling E. Efficient prematurity prevention is possible by pH-self measurement and immediate therapy of threatening ascending infection. Eur J Obstet Gynecol Reprod Biol. 2004 115:148-53. PMID 15262346

[edit] Bibliography

5. Khader YS, Ta’ani Q. Periodontal diseases and the risk of preterm birth and low birth weight: a meta-analysis. J Periodontol 2005;76:161-5.

[edit] See also

• WalkAmerica an annual walking-for-charity event that has raised more than $1.7 billion since 1970 to prevent premature birth

[edit] External links

• Prematurity - resource site from the March of Dimes
• Share Your Story - online community for NICU families, from the March of Dimes
• Prematurity - resource site for parents of premature infants and children
• Primer on Preemies - from the Nemours Foundation