Identification of a High-Risk Pregnancy
A high-risk pregnancy is
one in which the mother or fetus has a significantly increased chance of death
or disability (Hobel, 1979). In order to achieve optimal perinatal outcome, all
factors contributing to mortality and morbidity in a particular pregnancy must
be identified and acted upon early.
The factors may be divided
into the categories of socio-economic, demographic, and medical
Socioeconomic Factors
Socioeconomic Status. The
many social factors that place a fetus at greater risk are interrelated. Such
conditions as
¨1
overcrowding
¨2
poor standards of housing and hygiene, and
¨3
poor nutrition are closely associated with high rates of infant and
child morbidity and mortality.
Poverty and low educational
status are at root of these problems, and in countries where social and
economic improvement has occurred, there has also been a decrease in perinatal
mortality (Chea et al, 1977).
Parental Occupation. Occupation of the father,
as a reflection of socioeconomic status, is related to profound differences in
the incidence of prematurity and infant mortality. Kessner and Colleagus (1973) have reported that the lowest
incidence of perinatal loss occurs in cases in which the father is in a
professional or managerial position, where as the highest rates of loss are
seen in situations in which the father is absent altogether.
It has further been
demonstrated that a correlation exists between the occupation of the mother’s
father and the incidence of perinatal loss; that is, women from a higher
socioeconomic background have a lower incidence of perinatal loss than those
from a less affluent one (Kessner et al, 1973).
Social Environment. The effects of maternal
social environment on the outcome of pregnancy are recognized to be both
multiple and profound. ‘Social environment’ itself is described as the
summation of numerous factors, including the family’s standards of health and
hygiene, housing and financial status, emotional and social support and so on.
The environment itself was
grossly unhygienic. Recurrent infections and ‘poor health’ were frequently
noted within the family. Educational needs were, for the most part, unmet and
ignored. The adverse influences of this history of social, emotional, nutritional
and financial deprivation on reproductive outcome were numerous.
Psychological High-Risk
factors. When
a woman becomes pregnant the entire family prepares for change. The support and
guidance that the family receives during this preparation period will influence
the family’s ability to cope with the stress of this pregnancy and with its
changes in family structure, as well as with other life stresses in the future.
Therefore, it is important to identify psychological maladaptation to
pregnancy. Maladaptations may increase anxiety, and it has been suggested
increased anxiety can cause physical complications during pregnancy, including
preterm labour (Crandon, 1979; Creasy, 1981).
Demographic Factors
Maternal Age. The relationship between
maternal age and pregnancy outcome has long been recognized. Studies have been
shown that the optimal age for childbearing is between 20 and 30 years, with a
steadily increasing risk of perinatal mortality when the woman is over 30 years
of age. Children of mothers 19 years and younger and the first born of mothers
35 years of age and older are at an increased risk for prematurity and other
pregnancy complications such as pregnancy-induced hypertension (PIH) and
congenital anomalies. Additionally, babies born to women over 35 years of age
have an increased risk of genetic abnormalities (Crandall et al, 1986).
Maternal Education. Correlation’s have been indicated between the number of
years of schooling completed by a pregnant woman and perinatal death rate,
birth weight, and the rate of neurologic abnormalities seen in the child at 1
year of age. As the length of the mothers education increases, perinatal
morbidity and mortality rates drop significantly.
Maternal Height. Short stature of the
mother (less than 5 ft) has been associated with increased perinatal morbidity
and mortality in several studies. The primary reason suspected for this
association is that short maternal stature may be a reflection of adverse
environmental conditions and poor nutrition as a child. Because stature relates
to pelvic dimensions, short women have a higher incidence of operative
delivery, including cesarean section because of cephalopelvic disproportion.
Maternal weight and Weight
Gain. Women
who are underweight or overweight for height and age at the beginning of
pregnancy are at risk for poor perinatal outcome (Abrams and Laros, 1986). Both
of these parameters reflect previous nutritional status of the mother.
¨4
Women who are underweight and or fail to gain the recommended 28 to 35
lb during pregnancy are at risk for having low-birth- weight babies.
¨5
Women who are overweight and or gain more than 35 lb during pregnancy
are at risk for developing
preeclampsia and having large- for - gestational age babies.
¨6
Fetuses weighing more than 4000 g are frequently associated with an
increased likelihood of dystocia during labour, fetal distress, maternal and
infant birth trauma, and consequently, an increased incidence of perinatal
morbidity and mortality.
Previous Obstetric Problems
In women who have had an
obstetric complication or a perinatal loss, there is a tendency for the problem
to ‘repeat’ in a subsequent pregnancy. This is true for all of the factors
listed in the high-risk pregnancy classification.
History of Infertility. Conceptions following
medical or surgical treatment of infertility carry a considerable high-risk
factor. There is a high prevalence of multiple gestation and associated preterm
labour in women treated for infertility, and, therefore, an increase in the
perinatal morbidity and mortality rates.
Previous Ectopic Pregnancy
and Spontaneous Abortion. The incidence of
infertility in patients who have had an ectopic pregnancy is high, as is the
chance of a repeat ectopic conception (Kadar and Romero, 1990). In women who
have had two or more spontaneous abortion, the risk of a repeat abortion is
significantly increased.
Previous Stillbirth or
Neonatal Death. A history of a previous perinatal death, especially if the cause is
unknown, is an indication of high-risk status.
Uterine/Cervical Abnormality. Abnormalities of the uterus/ cervix such as a bicornuate
uterus, uterine septum, and incompetent cervix are frequently associated with
repeated spontaneous abortions and premature labour.
Previous Premature Labour. Premature labour is one of
the most challenging problems facing perinatal health care providers (Mc
Cormick, 1985). A woman who has
had a previous premature labor has a significantly higher chance of delivering
prematurely with a subsequent pregnancy.
Depending on the etiology of the preterm birth, the history of one
previous preterm birth is associated with a risk of recurrence of 25 to 50
percent, and the risk increases with each subsequent preterm birth (Creasy,
1990). There is also an increased chance that the patient will have a
stillbirth or neonatal death.
Previous Macrocosmic
Infant. A macrocosmic infant is one who, at
term, weighs more than 4000 g or is large for his or her gestational age. A
woman who has previously had, or is suspected of carrying, a large infant is at
risk for having or developing diabetes during pregnancy, with all its
concomitant problems. The infants themselves are at increased risk for
morbidity (including low newborn blood sugars) and mortality as a result of
unstable maternal metabolic condition, placental insufficiency, and even if the
mother is not diabetic, birth trauma due to difficult delivery, shoulder
dystocia, and other complications.
Grandmultiparity. Increasing parity
increases the risk of pregnancy wastage both in terms of higher mortality rates
and an increased risk of neurologic anomaly. In general, the lowest perinatal
mortality rate and incidence of obstetric complication occurs in second and
third pregnancies, and the highest in fifth and subsequent pregnancies. The frequency of anemia, hypertensive
disease of pregnancy, antepartum and postpartum hemorrhage, as well as the
number of cesarean sections, almost doubles for each of these complications in
women of lower parity.
Maternal Medical
History/Status.
Certain maternal disease diagnosed
prior to pregnancy, at the time of initial physical examination or at any time
during the pregnancy, may have a significant for both fetus and mother. These
are:
Maternal Cardiac Disease. The diagnosis of organic
heart disease includes:
¨
rheumatic heart disease
¨
hypertensive heart disease and
¨
congenital heart disease.
Fetal death rates are
substantially increased in women with any of these diagnosis; in fact, the
stillbirth rate is doubled compared with that in women without organic heart
disease.
The presence of organic
heart disease also significantly increases the risk of delivery of a
low-birth-weight infant (< 2500 g).
Maternal Pulmonary Disease.
Bronchial asthma is a
rather common respiratory disease; pregnancy does not seem to have any
consistent effect on it.
¨
The effect of pregnancy on asthma generally follows the rule of thirds:
one third of patients improve during pregnancy, one third remain unchanged, and
one third deteriorate.
¨
The fetuses may be at increased risk for intrauterine growth
retardation, preterm delivery, stillbirth, or neonatal death (Benedetti, 1990).
Diabetes Mellitus.
Diabetes is deleterious to
pregnancy in a number of ways. The adverse maternal effects that are likely to
be encountered are as follows:
1.
The likelihood of preeclampsia/eclampsia is increased fourfold.
2.
Infection occurs more often and is likely to be more severe.
3.
The fetus frequently is macrocosmic, and its size may lead to difficult
delivery with injury to the infant and the birth canal.
4.
The tendency for fetal condition to substantially deteriorate prior to
the onset of labor, as well as the possibility of dystocia, increases the
frequency of cesarean section with its incumbent maternal risk.
5.
Postpartum hemorrhage is more common
6.
Polyhydramnios is common
Maternal diabetes also affects the fetus/neonate in a variety of ways:
7.
Perinatal death rate is considerably higher.
8.
Morbidity as a result of birth trauma or respiratory distress syndrome
is common.
9.
Congenital anomalies, including sacral agenesis or anencephaly, open
spina-bifida, and cardiac anomalies, are more frequent.
10.The infant is more likely to inherit
diabetes.
11.Persistent maternal hyperglycemia probably
contributes to the increased risk of intrauterine death, respiratory distress
syndrome, hypoglycemia, and other morbidity (Gabbe, 1991)
Maternal Thyroid Dysfunction.
Thyroid disease appears to
have an adverse effect on pregnancy outcome.
¨
Hypothyroidism results primarily in an increase in the stillbirth rate.
¨
Hyperthyroidism shows a slight association with increased neonatal
mortality rate, a significant increase in the frequency of delivery of
low-birth-weight infants, and an overall drop in the mean birth weight.
Once the diagnosis of
thyroid disease is made in pregnancy, therapy may be complicated by the
presence of the fetus. Drugs that may be beneficial to the mother can be
harmful to the fetus, and this must be taken into account when a therapeutic
decision is made (Burrow and Ferris, 1982).
Gastrointestinal/Hepatic
System Diseases.
With the exception of
hepatitis and appendicitis, maternal gastrointestinal diseases does not
generally cause any increased risk in pregnancy.
¨
Hepatitis appears to be associated with an increase in low-birth-weight infants
and an increased incidence of infection of the infant.
¨
Appendicitis appears to increase the rate of premature labor, fetal death, and
low-birth-weight infants most probably as a result of infection, regardless of
whether surgery is performed.
¨ Chronic Hypertension
In most cases of chronic
hypertension, high blood pressure is the only demonstrable finding.
Frequently, the babies of
mothers with chronic hypertension show evidence of intrauterine growth
retardation. The incidence of abruptio placenta and PIH also has been noted to
be increased.
Renal Disease / Urinary
Tract Disease
Renal diseases such as
glomerulonephritis, nephrotic syndrome, polycystic disease of the kidney, and
previous nephrectomy/renal transplant vary in their effect on pregnancy
outcome, depending on the severity of the disease. Most commonly, they are associated with increased risk for
¨premature labor,
¨intrauterine growth
retardation, and
¨placental insufficiency
leading to antepartum fetal distress.
Acute urinary tract
infection, if undiagnosed or untreated, may lead to premature labor (Pritchcard
et al, 1985).
Current Obstetric Status
Late or No Prenatal Care
Prenatal care that is
inadequate, late is the single greatest predictor of poor perinatal outcome,
particularly in regard to low-birth-weight infants (Sachs et al, 1987).
Antepartum Bleeding.
Antepartum Bleeding.
Antepartum bleeding is defined as bleeding from the vagina after the 28th week
of gestation and prior to the onset of labor. The etiology includes
1.Placenta previa,
2.abruptio placenta,
3.local causes such as cervical polyps or erosions,
and
4.unknown etiology in which a specific cause cannot
found.
Placenta previa, and consequent bleeding
from a placenta partly or wholly attached to the lower uterine segment, is a
complication frequently associated with multiparity and older gravidas. Women
who gave had a placenta previa tend to repeat this complication in subsequent
pregnancies.
Overall incidence of
placenta previa is 1 in 200 pregnancies at term. Incidence increases significantly with
maternal age, parity, previous placenta previa, and most importantly, previous
uterine surgery (Bender, 1987).
Maternal mortality
associated with placenta previa has been reduced to less than 1 percent, but
maternal morbidity from this complication is still high as 20 percent (Astrash
et al, 1990; Cavanagh, 1982).
Prematurity is the
prevalent cause of perinatal mortality associated with placenta previa. Despite
the availability of neonatal intensive care, the perinatal mortality rate
remains as high as 20 percent, with intrauterine hypoxia and developmental
anomalies also complicated the situation.
Abruptio placenta is described as the premature separation of normally
implanted placenta from the uterine implantation site.
Abruption of the placenta is most commonly
associated with hypertension of any origin, including preeclampsia. High parity
and history of previous abruption have been implicated. Other factors
implicated as possible causes of abruption are trauma, sudden uterine
decompression (particularly with polyhydramnios), short umbilical cord, and
uterine leiomyomas and anomalies. Recurrence rates of placental abruption range
from 1 in 6 to 1 in 18 pregnancies (Patterson, 1979).
Maternal mortality in abruptio placenta
ranges from 2 to 10 percent in severe cases with associated fetal death. Perinatal mortality approaches 35
percent, the major determinats being length of gestation and fetal condition at
the time of presentation (Clark, 1990).
In general, antepartum
bleeding is associated with significantly increased risks for premature labor
and delivery, intrauterine growth retardation, fetal and maternal anemia, and
perinatal death (Clark, 1990).
Multiple Gestation.
Perinatal mortality in
twins is 2 to 3 times higher than in single births. The predominant cause of
perinatal death is prematurity. Other major complications include
¨placenta previa,
¨intrauterine growth
retardation,
¨twin to twin transfusion,
¨prolapsed cord,
¨premature separation of the
second placenta, and
¨malformations.
Women with a multiple
gestation have an increased incidence of
¨preeclampsia,
¨anemia,
¨polyhydramnios, and
¨postpartum hemorrhage.
Pregnancy-Induced
Hypertension (PIH)
PIH is one of the
hypertensive disorders of pregnancy, and a major contributor to maternal,
fetal, and neonatal morbidity and mortality and mortality. Complications of PIH
are the second most common cause of maternal deaths (Atrash, 1990).
The incidence of PIH is
approximately 6 to 8 percent. PIH seems to be higher in blacks for each age and
parity group, and it runs in families. The incidence is also higher in young,
primiparous women and in women with twins, diabetes, chronic hypertension,
polyhydramnios, and hydatidiform mole. Approximately one third develop it in
subsequent pregnancies (Burrow and Ferris, 1982).
Maternal effects of PIH range from
relatively transient to serious morbidity, such as
¨renal damage or
¨cerebral vascular accident,
to death of the mother or fetus, or both.
Fetal problems include increased
incidence of
¨intrauterine growth
retardation,
¨abruptio placenta,
¨preterm birth,
¨stillbirth, and
¨mental retardation in
surviving offspring.
At present, it is not
possible to prevent PIH. It is possible, however, to identify patients who are
especially prone to develop the disease. Conditions that predispose a woman to
develop PIH include:
1.First pregnancy
2.Multiple pregnancy
3.Chronic hypertension
4.Hydatidiform mole
5.Chronic renal disease
6.Malnutrition
7.Diabetes
8.Hydrops fetalis
9.History of PIH in family or in previous pregnancy
10.Age less than 20 or greater than 30
11.Patient’s developing polyhydramnios
Premature Rupture of the Membranes
Premature rupture of the membranes, that is,
rupture prior to the onset of labor, is a major perinatal complication and is
responsible for at least 30 percent of preterm deliveries (Garite, 1990;
Kaltreider, 1980).
The incidence of premature
rupture of the membranes is reported to be 8 to 10 percent of all pregnancies
that extend beyond 20 weeks’ gestation (Garite, 1990; Gunn et al, 1970). It is
associated with a high perinatal mortality rate, attributable primarily to
delivery of premature, low-birth-weight infants.
Depending on management,
premature rupture of the membranes can also be associated with significant
perinatal morbidity, including
¨premature delivery,
¨maternal and/or fetal
infection, and
¨fetal respiratory distress
syndrome.
Other problems, such as
¨breech presentation,
¨prolapsed cord,
¨transverse lie,
¨a plastic lungs, and
¨positional limb deformities
of the fetus due to the lack of “cushioning” normally provided by amniotic
fluid, have also been reported. It is felt by several authors that preexisting
infection may contribute significantly to premature rupture of the membranes.
Intrauterine Growth
Retardation
Intrauterine growth
retardation (IUGR) complicates approximately 3 to 7 percent of all pregnancies.
Babies born at or below the
10th percentile of mean weight for gestation are at greater risk of antepartum
death, perinatal asphyxia, neonatal morbidity, and later developmental
problems. Babies with IUGR have a perinatal mortality rate that is 8 times that
of normal infants(Butler and Alberman, 1969).
Two types of fetal growth retardation’s
¨asymmetric and
¨symmetric have been
described
In asymmetric IUGR, there
is increasing disproportion in head-to-body ratios. This type of IUGR is the
more common and is known as “brain sparing”, because the last organ to be
deprived of essential nutrients is the brain.
Asymmetric IUGR is most
commonly caused by adverse effects applied during the later part of pregnancy.
A common example is placental insufficiency resulting from such conditions as
PIH, chronic hypertension, smoking, and alcoholism.
Symmetric IUGR is non-brain
sparing, occurs less commonly, and can be the result of an acute maternal
infection, chromosomal abnormalities in the fetus, maternal drug addiction, or
maternal malnutrition.
Table 1
Factors Causing fetal
Growth Retardation
Maternal Factors Causing
fetal Growth Retardation
Chronic lung disease
Cyanotic heart disease
Severe anemia’s
Malnutrition
Low calorie consumption
Malabsorption conditions
surgical bypass procedures
Smoking
Drug addiction
Placental Factors Causing fetal Growth Retardation
Small placenta in
hypertensive women
Circumvallate placenta
Abnormal implantation site
Abruptio placenta
Fetal Factors Causing fetal Growth Retardation
Congenital anomalies
Trisomies
Intrauterine infections
AIDS (Acquired
immunodeficiency syndrome)
TORCH) Toxoplasmosis,
Rubella, Cytomegalovirus
Rh Isoimmunization
The simple step of
determining a woman’s Rh status should be done at the initial examination for
all pregnant women. Every Rh-negative woman carrying a child fathered by an
Rh-positive man should be tested for antibodies in every pregnancy, starting
with the first prenatal visit. Past history should include the following:
1.History of transfusion incompatible blood
2.Outcome of previous pregnancies
a)
Rh factors of infants
b)
Severity of hemolytic disease
c)
Gestational age at intrauterine death, if any
3.
Existing conditions implicated in predisposition to Rh isoimmunization
a)
PIH
b)
External version
c)
Abruptio placenta
Once this information is
obtained, appropriate measures:
¨
amniocentesis,
¨
cordocentesis,
¨
intrauterine fetal transfusion, and
¨
planning for possible early delivery can be instituted.
¨
Prevention is the key to eradicating this disease.
¨
Prolonged Pregnancy.
Prolonged pregnancy is a common obstetric
problem with potentially profound consequences. Three definitions are important
at the onset:
1.
Postdatism- the pregnancy has gone beyond the expected date of birth.
2.
Prolonged pregnancy- the length of gestation has exceeded 42 weeks.
3.
Postmaturity- a pediatric diagnosis based on neonatal examination.
The incidence of prolonged
pregnancy ranges from 7 to 12 percent, with an average of approximately 10
percent.
The perinatal impact of
prolonged pregnancy may be severe: Perinatal mortality for these infants is
increased 2 to 3 times relative to term infants, 7 times. Morbidity includes
birth trauma, meconium aspiration, and hypoglycemia. Developmental defects in
surviving infants have been identified.
Habits / Habituation
Smoking during Pregnancy. Cigarette smoking during
pregnancy has been demonstrated to be detrimental to the fetus.
Table 2
Categorization of High Risk
Pregnancy Factors
Socioeconomic Factors
1.
Inadequate finances
2.
Poor housing
3.
Severe social problems
4.
Unwed, especially adolescent
5.
Minority status
6.
Nutritional deprivation
Demographic Factors
1.
maternal age under 16 or over 35 years
2.
overweight or underweight prior to pregnancy
3.
Height
4.
less than 5 feet
5.
Maternal education less than 11 years
6.
Family history of severe inherited disorders
Medial Factors
A.
Obstetric History
1.
History of infertility
2.
Previous ectopic pregnancy or spontaneous abortion
3.
Grandmultiparity
4.
Previous stillborn or neonatal death
5.
Uterine / cervical abnormality
6.
Previous multiple gestation
7.
Previous premature labour delivery
8.
Previous prolonged labor
9.
Previous cesarean section
10.
Previous low-birth-weight infant
11.
Previous macrosomic infant
12.
Previous midforceps delivery
13.
Previous baby with neurologic deficit, birth injury, or malformation
14.
Previous hydatidiform mole or choriocarcinoma
B.
Maternal Medical History / Status
1.
Maternal cardiac disease
2.
Maternal pulmonary disease
3.
Maternal metabolic disease-particularly diabetes mellitus, thyroid
disease
4.
Chronic renal disease, repeated urinary tract infections, repeated
bacteriuria
5.
Maternal gastrointestinal disease
6.
Maternal endocrine disorders (pituitary, adrenal)
7.
Chronic hypertension
8.
Maternal hemoglobinopathies
9.
Seizure disorder
10.
Venereal and other infectious diseases
11.
Weight loss greater than 5 pounds
12.
Malignancy
13.
Surgery during pregnancy
14.
Major congenital anomalies of the reproductive tract
15.
Maternal mental retardation, major emotional disorders
C.
Current Obstetric Status
1.
Late or no prenatal care
2.
Rh sensitization
3.
Fetus inappropriately large or small for gestation
4.
Premature labor
5.
Pregnancy-induced hypertension
6.
Multiple gestation
7.
Polyhydramnios
8.
Premature rupture of the membranes
9.
Antepartum bleeding
a)
Placenta previa
b)
Abruptio placenta
10.
Abnormal presentation
11.
Postdatism
12.
Abnormality in tests for fetal well-being
13.
Maternal anemia
D.
Habits / Habituation
1.
Smoking during pregnancy
2.
Regular alcohol intake
3.
Drug use