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Introduction
Teenage pregnancy is considered to be a problem in both developing and developed countries. This is especially true in the developing countries due to 90% of all reported cases are in these countries1. Reports from the Reproductive Health Bureau, Ministry of Public Health showed an increase in unwanted pregnancy below the age of 20 from 13.9% in 2004 to 16.5% in 20112. The reports of the incidence of teenage pregnancy in Thailand ranged from 9.0% to 36.5% depending on duration, places and targeted population that were studied3-7.
Teenage pregnancy is itself a risk factor to both the mother and the newborn. Studies have shown more maternal complications such as anemia, pregnancy induced hypertension in teenage pregnancy when compared with the older group4,6-11. Maternal death and socio-economic problems were also higher in teenage pregnancies1,12. There was also an increase in neonatal complications and neonatal death13,14,16,,18,19. There were different results in the previous studies especially when they were analyzed and adjusted for other factors such as race, education, antenatal care6,13,15,16. This study aimed to investigate the clinical outcomes of teenage pregnancies compared with adult pregnancies and the effects of antenatal care on clinical outcomes of teenage pregnancies.
Materials and Methods
A retrospective cohort study was undertaken and permitted by the Ethics Committee of Chonprathan hospital. The study was performed in teenage pregnant women (aged below 20 years) and adult pregnant women (aged 20 to 34 years), regardless of ethinicity who were primigravida and delivered at Chonprathan hospital during 1 October 2011 to 30 September 2012. All medical records were reviewed for demographic characteristics, histories of pregnancies and deliveries of mothers and babies. The outcomes of the study were divided into three groups:
|
Groups of outcomes |
Specific measures |
|
1. Complications of pregnancy |
Anemia (Hct <33 %), pregnancy induced hypertension (PIH), premature rupture of membrane (PROM), antepartum / postpartum hemorrhage (APH / PPH) |
|
2. Perinatal outcomes |
Mode of delivery |
|
3. Neonatal outcomes |
Stillbirth, premature baby (gestational age< 37 wk), low birthweight infant (birthweight< 2,500 gm), small for gestational age (SGA), appropriate for gestational age (AGA), large for gestational age LGA), APGAR score at 1 and 5 minutes |
Statistical analysis
An estimation of sample size for the present study was based on a difference in the preterm labor incidences, as the primary outcome between women whose first pregnancy was at teenage (15%) and those at age 2034 years (8%)9, given the statistical significance level of 0.05 and statistical power of 80%. The calculation required at least 180 samples for the study group (teenage pregnancies), and 540 for the comparison group (adult pregnancies).
Continuous variables, including hematocrit, gestational age and birth weight were summarized using mean for central tendency and standard deviation for distribution. Comparison of these continuous variables between the two groups was subjected to students t-test. Frequency of prenatal visits, complication of pregnancies, perinatal and neonatal outcomes included severity levels based on APGAR scores were described in percentage for each group. Comparison of outcomes between the teenage and adult groups and across prenatal visit frequency (none, 1-3 and 4 times) in teenage groups was subject to Chi-square test or Fishers exact test, as appropriate. For determining magnitude and statistical significance of an association of the neonatal outcomes with ages of mothers or antenatal care, a logistic regression was applied using the variables for adjustment.
Results
During the one year of study period, a total of 734 women of first pregnancy were conformed to the selection criteria. There were divided into two groups of 231 teenagers (age 17.4 + 1.4 years with the minimum of 13 years) and 503 adults (age 26.2 + 4.2 years). Teenage group had relatively lower education, more unemployment or informal sector employment (Table 1) and had no or fewer prenatal visits in a greater proportion (Table 2) than the adult group (p<0.05). On average, hematocrit during pregnancy of teenagers (34%) was relatively lower than that of adults (34.7%) (p<0.05). Other complications including PIH, PROM, APH and PPH were not significantly different between the two groups (Table 2).
Table 1 General characteristics of teenage and reproductive age mothers
|
Characteristic |
Teenage pregnancy (N=231) |
Reproductive age pregnancy (N=503) |
p-value |
|
Age (yr.) (mean + SD) |
17.4 + 1.4 |
26.2 + 4.2 |
< 0.001* |
|
Race (%) |
|
|
0.110 |
|
-Thai |
95.24 |
92.64 |
|
|
-Burmese |
1.30 |
3.98 |
|
|
-Cambodian |
2.16 |
0.80 |
|
|
-Laotian |
1.30 |
2.39 |
|
|
-Vietnamese |
0.00 |
0.20 |
|
|
Education (%) |
|
|
<0.001* |
|
-Elementary and lower |
16.97 |
9.02 |
|
|
-High school |
83.03 |
50.41 |
|
|
-Above high school |
0.00 |
40.57 |
|
|
Employment status (%) |
|
|
<0.001* |
|
-Unemployment |
62.77 |
26.44 |
|
|
-Informal sector** |
27.71 |
19.88 |
|
|
-Formal sector*** |
9.52 |
53.68 |
|
* Statistical significance (p<0.05)
** unskilled workers, housemaids, merchants, independently or self-employed
*** employed by private business and public settings
Table 2 Antenatal care and complication of pregnancy
|
Characteristic |
Teenage pregnancy (N=231) |
Reproductive age pregnancy (N=503) |
P value |
|
Numbers of prenatal visits (%) |
|
|
0.001* |
|
-None |
6.52 |
2.20 |
|
|
-1 time |
6.52 |
3.81 |
|
|
-2 times |
10.87 |
6.61 |
|
|
-3 times |
10.87 |
8.02 |
|
|
-4 times |
65.22 |
79.36 |
|
|
% Hct (Mean + SD) |
34.0 + 3.2 |
34.7 + 3.3 |
0.010* |
|
Hct < 33% (%) |
30.74 |
24.85 |
0.094 |
|
> 33% (%) |
69.26 |
75.15 |
|
|
PIH (%) |
3.03 |
4.57 |
0.327 |
|
APH (%) |
0.00 |
0.40 |
1.000** |
|
PROM (%) |
8.23 |
8.75 |
0.814 |
|
PPH (%) |
0.00 |
1.79 |
0.064** |
* Statistical significance (p<0.05)
** Based on Fishers exact test
Teenage group underwent Caesarean section or vacuum / forceps extraction in a lower proportion (30.7%) than adult group (56.7%) (p<0.001) (Table 3). One and two stillbirths were found in the teenage and adult groups, respectively. For outcomes to newborns, gestational age at delivery for teenage group was 38.2 + 2.6 weeks (minimum 24 weeks) and for adult group was 38.5 + 2.0 weeks (minimum 26 weeks). The premature babies were more common in teenage group (15.6%) than in adult group (10.2%) (p=0.036). The weight if the babies born of teenage group were 2,869.9 g. on average, compared with 3,030.1 g. for adult group (p<0.001). As a consequence, the low birthweight infants were more common in the teenage group (16.0%) than in the adult group (11.1%) (p=0.065). Teenage group had a slightly higher proportion (6.1%) of SGA than the adult group (4.4%). A low APGAR score (0 3) at 5 min. was slightly more common in the teenage group (2.2%) than the adult group (0.2%) (p= 0.016).
When using logistic regression analysis and adjusted for levels of education, employment status and antenatal care, the teenage group had more premature and low birthweight babies than in adult group (7.7%, 4.9%, respectively) (Table 4) but statistically non-significant.
When compared the teenage pregnancies across prenatal visit frequency (none, 1-3 times or incomplete and 4 times or complete antenatal care), there were few differences in the mean age between the three groups (17.3 + 1.6, 16.8 + 1.6 and 17.6 + 1.3 years, respectively) but no difference in the levels of education and employment status (Table 5). The non-antenatal care group had lower level of hematocrit than the complete antenatal care group (32.2% vs. 34.3%, p=0.047). There were correlations between gestational age, birth weight and prenatal visit frequency. Non-antenatal care group had more premature and low birthweight babies than the other two groups (p<0.001) (Table 5). A low APGAR score (0 3) at 1 and 5 min. was most common in the non-antenatal care group.
In teenage pregnancies when using logistic regression analysis and adjusted for age of mother, level of education and employment status, the study showed that antenatal care could reduce risk of preterm labor and low birthweight infant especially when there was complete antenatal care, 91.6% for preterm labor (P=0.002) and 80.6% for low birthweight infant (p=0.047) (Table 6).
Table 3 Perinatal and neonatal outcomes
|
Characteristic |
Teenage pregnancy (N=231) |
Reproductive age pregnancy (N=503) |
p-value |
|
Delivery mode (%) |
|
|
<0.001* |
|
-Normal delivery |
69.26 |
43.34 |
|
|
-Caesarian section |
30.74 |
55.06 |
|
|
-Vacuum extraction (V/E) |
0.00 |
0.80 |
|
|
-Forceps extraction (F/E) |
0.00 |
0.40 |
|
|
-Breech assisting |
0.00 |
0.40 |
|
|
Stillbirth (%) |
0.43 |
0.40 |
0.945 |
GA Mean + SD (wk.) |
38.2 + 2.6 |
38.5 + 2.0 |
0.067 |
|
GA < 37 wk. (%) |
15.58 |
10.18 |
0.036* |
|
> 37 wk. (%) |
84.42 |
89.82 |
|
|
Birth weight Mean + SD (g.) |
2,869.9 + 522.2 |
3,030.1 + 499.8 |
<0.001* |
|
Birth weight < 2,500 g. (%) |
16.02 |
11.13 |
0.065 |
|
< 2,500 g. (%) |
83.98 |
88.87 |
|
|
Newborn characteristic (%) |
|
|
0.180 |
|
-AGA |
90.04 |
88.67 |
|
|
-SGA |
6.06 |
4.37 |
|
|
-LGA |
3.90 |
6.96 |
|
|
APGAR score at 1 min. (%) |
|
|
0.225 |
|
-0 3 |
4.33 |
2.40 |
|
|
-4 7 |
3.46 |
5.19 |
|
|
-8 10 |
92.21 |
92.42 |
|
|
APGAR score at 5 min. (%) |
|
|
0.016* |
|
-0 3 |
2.16 |
0.20 |
|
|
-4 7 |
1.73 |
1.00 |
|
|
-8 10 |
96.10 |
98.80 |
|
* Statistical significance (p<0.05)
Table 4 Association between teenage pregnancy and neonatal outcomes
|
Pregnancy |
Premature baby |
Low birthweight infant |
|
Odds ratio* |
p-value |
95% CI |
Odds ratio* |
p-value |
95% CI |
|
Adult |
1.000 |
- |
- |
1.000 |
- |
- |
|
Teenage |
1.077 |
0.805 |
0.60 1.93 |
1.049 |
0.867 |
0.60 1.84 |
* adjusted for level of education, employment status and antenatal care
Table 5 Characteristics and outcomes in teenage pregnancy and prenatal visit frequency
|
Characteristic |
Number of ANC |
p-value |
|
None (N=15) |
1 3 (N=65) |
4 (N=150) |
|
Education (%) |
|
|
|
0.750 |
|
-Elementary and lower |
22.22 |
19.35 |
15.75 |
|
|
-High school |
77.78 |
80.65 |
84.25 |
|
|
Employment status (%) |
|
|
|
0.754 |
|
- Unemployment |
60.00 |
61.54 |
63.33 |
|
|
- Informal sector |
26.67 |
32.31 |
26.00 |
|
|
- Formal sector |
13.33 |
6.15 |
10.67 |
|
|
%Hct (Mean + SD) |
32.2 + 3.6 |
33.8 + 3.3 |
34.3 + 3.0 |
0.041c |
|
Hct < 33% (%) |
53.33 |
33.85 |
26.67 |
0.079 |
|
> 33% (%) |
46.67 |
66.15 |
73.33 |
|
|
GA Mean + SD (wk.) (min. max.) |
34.7 + 5.2 (24.0 40.0) |
37.2 + 2.8 (28.0 41.0) |
39.0 + 1.4 (34.0 42.0) |
<0.001a,b,c |
|
GA < 37 wk. (%) |
46.67 |
29.23 |
6.00 |
<0.001* |
|
> 37 wk. (%) |
53.33 |
70.77 |
94.00 |
|
|
Birth weight Mean + SD (g.) (min. max.) |
2,270.0 + 820.3 (560.0-3,250.0) |
2,725.2 + 604.9 (1,160.0-3,775.0) |
2,995.5 + 371.4 (1,745.0-3,975.0) |
<0.001a,b,c |
|
Birth weight < 2,500 g. (%) |
46.67 |
27.69 |
7.33 |
<0.001* |
|
< 2,500 g. (%) |
53.33 |
72.31 |
92.67 |
|
|
APGAR at 1 min. (%) |
|
|
|
0.005* |
|
-0 - 3 |
20.00 |
7.69 |
1.33 |
|
|
-4 - 7 |
6.67 |
3.08 |
2.67 |
|
|
-8 - 10 |
73.33 |
89.23 |
96.00 |
|
|
APGAR at 5 min. (%) |
|
|
|
<0.001* |
|
-0 - 3 |
20.00 |
1.54 |
0.67 |
|
|
-4 - 7 |
6.67 |
4.62 |
0.00 |
|
|
-8 - 10 |
73.33 |
93.85 |
99.33 |
|
* Statistical significance (p<0.05)
a difference between no ANC group and incomplete ANC group, statistical significant
b difference between incomplete ANC group and complete ANC group, statistical significant
c difference between no ANC group and complete ANC group, statistical significant
Table 6 Association between antenatal care grouping and neonatal outcomes in teenage pregnancy
|
ANC |
Premature baby |
Low birthweight infant |
|
Odds ratio** |
p-value |
95% CI |
Odds ratio** |
p-value |
95% CI |
|
None |
1.000 |
- |
- |
1.000 |
- |
- |
|
Incomplete |
0.467 |
0.331 |
0.101 - 2.166 |
0.813 |
0.799 |
0.166 - 3.985 |
|
Complete |
0.084 |
0.002* |
0.017 - 0.416 |
0.194 |
0.047* |
0.039 - 0.975 |
* Statistical significance (p<0.05)
** adjusted for age of mother, level of education and employment status
Discussion
Teenage pregnancy is an important social problem of Thailand and is a health risk factor for both mothers and newborns. According to many studies in both Thailand and other countries3,4,6,7,9,11,13-16,18,19, most teenage pregnancies had a lower educational status, were unemployed, and in a lesser economical status when compared to the adult pregnant population. This study also confirmed that lesser education and being unemployed were common factors in teenage pregnancy. Similar to other studies, teenage pregnancy tended to have incomplete or non-antenatal care when compared to the adult pregnancy 4-9,16. Some studies showed that teenage mothers tended to be of a higher risk of anemia4,6-11, while some studies differed3,5,17. In this study, hematocrit levels of teenage group were significantly lower than that of the adult group. There was no difference between the groups for the other maternal complications, like most studies that showed insignificant difference between the two groups4,5,7-9,11. However, postpartum hemorrhage was higher in the adult group in Thaithae S and Thato R report6. This study showed that teenage group had a higher chance for normal delivery than adult group. In the other studies, teenage mothers either delivered by normal labor or Caesarian section more than the adult group 3-9,11 while other study showed no difference14. The difference of birth preference depends on maternal cooperation, pelvic dimensions, and baby size.
Many studies have shown that preterm labor and low birthweight infants were associated with teenage pregnancy3-5,7-,9,11,13,14,16,18. Our finding was consistent with these but there was insignificant correlation when the data was sub-analyzed for education, occupation and antenatal care. This was consistent with the results of Thaithae S and Thato R6. Results from Stewart CP et al15 found that when race, education, smoking history, and BMI were considered, maternal young age was significantly related to preterm labor but not related to birth weight of the newborn. Teenage pregnancy was also associated to preterm labor and lower birth weight newborn when the data was sub-analyzed for social aspects, race, and baby gender in the studies by Khashan AS Baker PN and Kenny LC13. This was also observed in Chen XK et al study16 when race, marital status, smoking and alcoholic drinking during pregnancy, antenatal care was considered. Preterm labor and lower birth weight newborn in teenage pregnancy may be associated with biological factors of teenager and environmental factors. Most studies have shown that teenage pregnancies have poor social opportunities such as education, occupation, and poor antenatal care3-9,11,13-16,18. For the other outcomes of the babies, there were no differences for stillbirth and APGAR score at the first minute between the two groups. There was a difference of APGAR score at the fifth minute with the teenage pregnancy group having a lower score (0-3) more than the comparison. Many studies have different results, some studies showed that stillbirth5,14, small for gestational age infant8,15, low APGAR score5,11,16 were significant in teenage pregnancies but in the other studies there were no differences4,6-9. These different results may be due to the variation between age grouping in each studies.
In developed countries with adequate antenatal care, there were no difference in risk of preterm labor or low birthweight infant for teenage pregnancy when compared to the adult pregnancy20. Heuston WJ, Quattlebaum RG and Benich JJ21 studied the benefit of antenatal care in teenage pregnancy, showed that antenatal care could reduce cost by decreasing the cost of taking care of the low birthweight infant. In developing countries with high incidence of teenage pregnancy, had a higher risk of poor antenatal care. And in the group that had adequate antenatal care the baby survived more than the poorer group22. A study in Bangladesh by Khatun S and Rahman M23 proved a positive relation for higher birth weight with every antenatal visit. In Thailand, Suebnukarn and Phupong V24 studied in teenage pregnancies of less than 15 years old found that incomplete or non-antenatal care group had a higher chance of preterm labor and lower birth weight than the completed antenatal care group. This study compared none, incomplete and complete antenatal care groups of teenage pregnancy. The results were that antenatal care decreased the risk of preterm labor and low birthweight infant. This was especially true if the mother had complete antenatal care. Therefore, it should be encouraged to attend adequate antenatal care for all teenage pregnancies to decrease pregnancy related complication and risk to the newborn.
Conclusion
Teenage pregnancy is an important social problem in Thailand with increasing incidences. There are consequences to both mothers and newborns. Teenage pregnancies have a higher chance of preterm labor and lower birth weight in the newborns. Poor antenatal care is a crucial factor for this, so teenage pregnant woman should be encouragds to attend adequate antenatal care in order to prevent complications.
References
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