MCHB/EPI Miami Conference — December 7 - 9, 2005

Maternal Age: In the Tails of the Distribution

YIWEI TANG: Hi, good morning. My topic is to talk about the youth factor of maternal age on pregnancy, births, and infant outcomes. This study is from Florida . Population base cohort study from '96 to 2001 and this study was conducted in pediatrics department in the University of Florida .

First, I will give some background and then I will talk about some study questions, method and give some results and some discussion. First, we know the adolescent, the child bearing adolescent that has been associated with, was associated with numerous adverse outcomes, like in pregnancy outcomes we have increased risk in pre-term labor, anemia, eclampsia. In births outcomes we have high risk in SGA, low birth weight, stillbirths. In infant outcomes we have high risk in neonatal mortality, post neonatal mortality, and infant mortality. But some literature still showed some controversy conclusions and some authors found no difference between adolescents and older mothers in birth weight, gestational age, pre-term delivery, prenatal mortality, and the neonatal mortality.

In our study we want to evaluate if there's an association of young maternal age and adverse pregnancy, births and infant outcomes, after controlling for socio-demographic health behavior factors. In this study we used 6 years Florida births, cohort from '96 to 2001. The sample size is about 1.2 million live births.

We used linked births and deaths records merged to medical eligibility file and a Florida birth defects registry. Here are the outcomes. In pregnancy, we have three outcomes, complication of pregnancy, complication of labor, delivery, C-section. In birth outcomes we have low birth weight, very low birth weight. For infant outcomes we have neonatal mortality, post neonatal mortality, infant mortality and birth defects. We also controlling for several socio-demographic health and behavior factors. We controlled the maternal age, race, education, marital status, Medicaid, infant sex. We also controlled for a number of previous live births, previous non-live births, plurality, adequacy of prenatal care, smoking and drinking.

We used Poisson regression models to estimate the independent effect of each explanatory factors on each outcome. In the readouts we found over 1.2 million births during the 6 years value period. Around 13 percent were born to adolescents. Fifty-one percent born to mother aged 20 to 29. Thirty-six percent was born to mother older 30 years old.

This table shows the row rate for each outcome, group of mothers aged less than 20 years old and the age between 20 and 29. We found high risk in the very low birth weight, neonatal mortality, post neonatal mortality, infant mortality and also low birth weight, complication of labor and delivery and complication of pregnancy.

And this table shows the adjusted relative risk of young maternal age of 9 adverse outcomes. We found 3 increased risk for young maternal age in very low birth weight, post neonatal mortality, infant mortality. And then we also found the protective effect of young maternal age, complication of labor and delivery, c-section and birth defect.

So in this study we found the young maternal age was associated with reduced risk of 2 adverse pregnancy outcomes and the 1 adverse birth outcome. Also young maternal age was associated with high risk of 1 birth outcome and 2 mortality outcomes. The high risk of post neonatal mortality is most likely related to the psychological immaturity of adolescent mothers. And the increased the efforts to enroll adolescents in the family planning program may result in postponing maternity to optimal age span 20 to 29 and to increase the intra-contraception period. In Florida right now we have a campaign called Two Years Apart is Baby Smart. So both strategies have potential for lowering post neonatal and infant mortality among young maternal mothers.

The next step we think we need to go further into more detail about the adolescent age group. We plan to divide either into less than 15 years old, 15 to 17, 18 to 19 years old, for each outcome. Actually I already run the program, but there's some problem and our results license has been expired so I cannot present the result to anybody else. So if you have interest you can email me. I will send the read out to you. So, we thank the Florida Department of Health and other Florida agency. We also thank University of South Florida and the University of Florida . Any questions?

UNKNOWN SPEAKER: I have one. Could you speak a little bit more about the program to, I'm looking for the name, I don't think I have it in here, but it was the program to space more of the pregnancies, for teen pregnancies.

YIWEI TANG: Oh, two years apart?

UNKNOWN SPEAKER: Yeah, could you say a little bit more about what that is doing or what the program is about?

YIWEI TANG: Actually I'm not very familiar with this program. Actually Dr. Rawls just gave this presentation to me before I leave, so, I will let him to email you what the program is about.

UNKNOWN SPEAKER: Okay. Thank you.

YIWEI TANG: Okay.