Click to edit Master text styles
Second level
Third level
Fourth level
Fifth level
‹date/time›
‹footer›
‹#›
------=_NextPart_01C650EB.8FDAB6D0
Content-Location: file:///C:/2358DE72/humbio0405R2_files/master03.xml
Content-Transfer-Encoding: quoted-printable
Content-Type: text/xml; charset="utf-8"
‹header›
‹date/time›
‹footer›
‹#›
------=_NextPart_01C650EB.8FDAB6D0
Content-Location: file:///C:/2358DE72/humbio0405R2_files/pres.xml
Content-Transfer-Encoding: quoted-printable
Content-Type: text/xml; charset="utf-8"
![](3D"master03_background.gif")
Percentage of preterm births is associated with =
year
of mothers' age in African-American (AA) adolescent =
pregnancies<=
/span>
Jane Mitchell Rees, PhD, MS, RD.
Maternal Child Health Program and Adolescent Medicine Section
Departments of Health Services and Pediatrics
Schools of Public Health and Community Medicine and Medicine
University of Washington, Seattle, WA.
Partial Support: Grant T76-MC0=
0011
Health Resources and Services Administration, USDHHS
![](3D"slide0004_image001.gif")
Introduction
=
•Seeking biological explanation for lack of
fitness in infants of adolescents is "unwarranted" (Geronimus 1986)
•
•
•
•
![](3D"slide0024_image002.gif")
Introduction
=
•Seeking biological explanation for lack of
fitness in infants of adolescents is "unwarranted" (Geronimus 1986)
•
•Life History Theory predicts decreased fitn=
ess
in infants of youngest mothers
•
•
![](3D"slide0027_image003.gif")
Introduction
=
•Seeking biological explanation for lack of
fitness in infants of adolescents is "unwarranted" (Geronimus 1986)
•
•Life History Theory predicts decreased fitn=
ess
in infants of youngest mothers
•
•Clinical and demographic studies in small
populations demonstrate AA adolescent mothers likely to bear pre-term infants (Marti=
n et
al., (CDC) 2003, Olausson et al., 1999, Hediger et al., 1997, Garn & Petz=
old
1983)
•
![](3D"slide0005_image004.gif")
Menarcheal age and age at conception of a typical group of AA
adolescents
Rees JM. 2005
(unpublished)
![](3D"slide0006_image007.gif")
Objective
=
•Evaluate influence of mothers’ age on
prevalence of preterm births to adolescents
![](3D"slide0007_image008.gif")
Methods
=
=
•National Center for Health Statistics Linked
Birth/Infant Death Data Sets – 1997-99
•
![](3D"slide0028_image009.gif")
Methods
=
=
•National Center for Health Statistics Linked
Birth/Infant Death Data Sets – 1997-99
•All US births linked to corresponding birth
certificates
•
![](3D"slide0029_image010.gif")
Methods
=
=
•National Center for Health Statistics Linked
Birth/Infant Death Data Sets – 1997-99
•All US births linked to corresponding birth
certificates
•1,757,793 singleton live births to AA mothers 10-54 y
![](3D"slide0030_image011.gif")
Methods
=
=
•National Center for Health Statistics Linked
Birth/Infant Death Data Sets – 1997-99
•All US births linked to corresponding birth
certificates
•1,757,793 singleton live births to AA mothers 10-54 y&#=
13;
•Percentage of infants born at <37 wk
gestation to mothers, at each year of age
•Analyzed those with ><=
span
style=3D'font-size:133%;color:white;mso-color-index:0'> 100 cases per y, a=
nd
gestational age or prenatal care category
![](3D"slide0031_image012.gif")
Methods
=
=
•National Center for Health Statistics Linked
Birth/Infant Death Data Sets – 1997-99
•All US births linked to corresponding birth
certificates
•1,757,793 singleton live births to AA mothers 10-54 y&#=
13;
•Percentage of infants born at <37 wk
gestation to mothers, at each year of age
•Results stratified by initiation of prenatal
care, representing socioeconomic status/engagement with the <=
/span>health care system =
![](3D"slide0012_image013.gif")
Population
Total births to AA (1997-99) 1,757,7=
93 100.0%
Preterm births 279,809 15.9%
<=
/span>
Preterms excluded (<100 cases/ y age) 129 0.05%
Reporting on prenatal care / preterm birth 265,584 100.0%
initiated during 1<=
/span>st trimester*
180,094 67.8%
*Exclusions (<100 in cases/ y age)
![](3D"slide0008_image014.gif")
Results
=
=
•Shown as plots of percent of preterm
births versus mother’s age
![](3D"slide0037_image015.gif")
Percent preterm births (<37 wks) by pren=
atal
care: US <=
span
style=3D'font-size:64%;color:white;mso-color-index:0'>1997-99 AA singleton=
live
births
![](3D"slide0018_image018.gif")
Percent preterm births (<37 wks) with and
without prenatal care: US 1997-99 AA
singleton live births
![](3D"slide0039_image021.gif")
Percent preterm births (<37 wks) with
prenatal care: =
US 1997-99 AA single=
ton
live births
![](3D"slide0038_image024.gif")
Percent preterm births (<37 wks) with
prenatal care: =
US 1997-99 AA single=
ton
live births
![](3D"slide0036_image027.gif")
Percent preterm births (<37 wks) with
prenatal care: =
US 1997-99 AA single=
ton
live births
![](3D"slide0011_image030.gif")
Conclusion
=
•Young age, representing lack of physical
maturation, is a strongly associated with preterm birth among AA gravidas decreasing
fitness as predicted by Life History Theory.
•
![](3D"slide0033_image031.gif")
Conclusion
=
•Young age, representing lack of physical
maturation, is a strongly associated with preterm birth among AA gravidas decreasing
fitness as predicted by Life History Theory.
•
•Socioeconomic status, represented by trimes=
ter
of initiation of prenatal care, does not negate this relationship.
![](3D"slide0042_image032.gif")
Conclusion
=
•Young age, representing lack of physical
maturation, is a strongly associated with preterm birth among AA gravidas decreasing
fitness as predicted by Life History Theory
•
•Socioeconomic status, represented by trimes=
ter
of initiation of prenatal care, does not negate this relationship
•
•While this association may be responsible f=
or a
relatively
small difference in overall preterm rate, it should be of intere=
st to
human biologists
![](3D"slide0023_image033.gif")
Odds ratios for term vs. preterm: U.S. 1997-1999 AA singleton first live births
Data shown when p<0.05
‹header›
‹date/time›
Click to edit Master text styles
Second level
Third level
Fourth level
Fifth level
‹footer›
‹#›
•This morning I will discuss the
prevalence of pre-term births among AA adolescent gravidas.
•I=
want
to thank Maternal, Child Health and Adolescent Medicine Programs and
especially HRSA for their support of my work.
… and the organization
committee for giving me the opportunity to present it today
•Some investigators assert adverse
outcomes of adolescent pregnancy are solely due to socioeconomic status.
•Geronimus’
conclusion that seeking a biological explanation for lack of fitness in
infants of adolescent is “unwarranted” is still very influential.
•LHT,
however, predicts decreased fitness in infants of youngest mothers.
•In
this case gestational age will be the token for fitness.
•Previous clinical and small populati=
on
studies have demonstrated frequent pre-term births to adolescent
gravidas.
•However,
results are often for ages in ranges… with multiple ethnic populations, and
little power to detect differences because of the size of samples.
•As background… shown here is the
relationship of age of conception to age of menarche in a typical clinical
sample of the AA population delivering before 18 years of age.
•…
since most studies have shown various dimensions of growth to have continu=
ed
through this period but to have ceased by age 20.
•
•We
could expect growth to be taking place throughout these years under normal
circumstances.
•My objective was to study the influe=
nce
of age, representing physical maturation, on the prevalence of pre-term bi=
rth…
as a token for fitness.
•Chose to study those in a 3 year
national population from the NCHS data sets.
•…
selecting those born in the US.
•Studied
the percentage born at less than 37 wk gestation by y of mothers’ age
=
… Examining those with at =
least
100 cases per age and gestational wk.
•Then stratified by initiation of
pre-natal care, representing socioeconomic status/engagement with the heal=
th
care system.
Here we see total US births to AA population.
… the pre-term births
… those excluded with less than 100 cases/y age
… the trimester initiated
… and those without prenatal care
•Results will be shown as plots, perc=
ent
pre-term births by year of mother’s age.
•RESULTS
•Percentage
of infants born pre-term inversely associated with each age of mothers fro=
m 12
- 22 y
• … for all births and births with pre-=
natal
care
•Precent
decreased from 27% to 14% during those ages
•Percentage
of pre-term births was unrelated to age between 22 and 30 y
•Changed
only 5% across that age range
•The
green line shows that there was little change in results for those who had=
prenatal
care.
•Without prenatal care there was a hi=
gh
increase in percentage of infants born pre-term,
•Percentage
preterm was still associated with mothers’ age until 22 y
•When prenatal care began in the 1rd=
trimester, percentage of infants born p=
re-term
inversely associated with each y of age 12 – 23?
•Association
of percentage of pre-term births unaffected by early initiation of prenatal
care
•When prenatal care began in the 2rd=
trimester, percentage of infants born p=
re-term
was inversely associated with each year of age 12 – 23 ?
•When prenatal care began in the 3rd=
trimester, percentage of infants born p=
re-term
inversely associated with each year of age 12 – 22.
•Thus,
the association of percentage of pre-term births was unaffected by initiat=
ion
of prenatal care.
•I conclude that age, representing
physical maturation, is clearly associated with prevalence of pre-term bir=
th
representing infant fitness.
•And
further, the association is not negated by prenatal care patterns.
Logistic regression results:
Dependent variable – Term (1)
Pre-term (0).
Independent variables – <=
/span>Prenatal
care: Yes (1) No (0)
Marital Status: Married (1) Unmarried (=
0)
Appropriate Educ=
ation:
Yes (1) No (0)
Prenatal care results in an odds of 2.5 to 3.0 for
delivering a term vs. a pre-term infant.
Married status and Appropriate
education results in a small improvement in the odds for a term infant.=
3;
[P value on chart]
' + ENDSHOW_MESG + '
![](3D"notes_flag.gif")
No=
tes![](3D"buttons.gif")
