# MECHANISMS OF TERM AND PRETERM LABOR

> **NIH NIH R01** · CORNELL UNIVERSITY · 1994 · $214,198

## Abstract

Preterm labor is the biggest single cause of neonatal mortality and
morbidity.  We propose experiments in chronically instrumented pregnant
rhesus monkeys in the last third of pregnancy.  This chronic whole animal
model is the closest available to study mechanisms of labor as they relate
to human clinical situations.

Different patterns of myometrial activity exist during pregnancy. Through
the majority of pregnancy, epochs of myometrial activity lasted several
minutes and generate small changes in intrauterine pressure. These epochs,
contractures, can be distinguished from the approximately one minute long
contractions that occur at labor and delivery and other situations.  When
labor and delivery occurs, contractures are replaced by contractions.  A
thorough understanding of the mechanisms that control this switch from
contractures to contractions is necessary to determine the causes of term
and preterm labor.

We hypothesize that changes in the physiology of oxytocin (OT) play
important roles in the shift from contractures to contractions that occurs
at normal term in our experimental model.  Our Specific Aim is to
investigate the role of oxytocin (OT) in the mechanisms active at term
labor and to conduct studies that will determine whether the switch from
contractures to contractions represents a true circadian rhythm of
intrinsic origin or merely reflects external 24h rhythms.  Our proposed
studies will utilize both in vivo and in vitro techniques.  Parturition is
a multifactorial system.  To obtain precisely quantifiable and
interpretable results we propose five experiments in each of which we will
change a single variable at a time in a carefully controlled fashion.

We provide preliminary data for four of the five proposed studies.  For the
first time we have been able to study an instrumented pregnant monkey under
constant lighting conditions.  We have produced preliminary data to show
that maternal body temperature and the switch from contractures to
contractions can free run.

These studies will provide information on the regulation of different
patterns of myometrial activity and suggest procedures for diagnosis and
management of preterm labor (e.g. development of efficacious myometrial
antagonists) in women.

## Key facts

- **NIH application ID:** 2199874
- **Project number:** 5R01HD026203-05
- **Recipient organization:** CORNELL UNIVERSITY
- **SAM.gov UEI:** G56PUALJ3KT5
- **Principal Investigator:** PETER W. NATHANIELSZ
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1994
- **Award amount:** $214,198
- **Award type:** 5
- **Project period:** 1990-04-01 → 1995-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/2199874

## Citation

> US National Institutes of Health, RePORTER application 2199874, MECHANISMS OF TERM AND PRETERM LABOR (5R01HD026203-05). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/2199874. Licensed CC0.

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