Biological Impacts of Rising Temperatures on Maternal, Fetal, and Newborn Health: A Cohort Study (BIRTH Cohort)
试验速览
- 阶段
- 不适用
- 状态
- 招募中
- 入组人数
- 6,000
- 试验地点
- 3
- 主要终点
- Incidence of Low birthweight (LBW)
研究概览
简要总结
The goal of this study is to learn how being exposed to high environmental temperatures during pregnancy affects the health of pregnant women and their babies. The study also aims to understand how the body responds to heat stress during pregnancy and how this might lead to pregnancy complications and birth problems like early birth or low birth weight.
The main questions that the study aims to answer are:
- What are the acute and chronic effects of environmental heat exposure on pregnancy and birth outcomes across different trimesters?
- Through which biological pathways does heat stress impact maternal, fetal, and infant health across varying gestational ages?
- How do socio-demographic factors, maternal characteristics, and nutritional status of women modify the relationship between environmental heat exposure and adverse pregnancy outcomes?
The study will take place in rural parts of Sindh, Pakistan. These areas often experience extreme heat and have limited access to electricity or cooling systems like fans or air conditioners.
This study will include pregnant women who are in their first trimester (under 14 weeks of pregnancy). Before starting any study activities, researchers will explain the study to each woman in a language she understands and ask for her written permission to take part (informed consent).
At the beginning of the study, participants will visit a study clinic. During this visit, researchers will check their height and weight, perform an ultrasound, and collect a small amount of blood for testing. Participants will also be asked to wear a small device that measures the air temperature and humidity in their surroundings.
The researchers will follow each participant during her pregnancy, with visits during the second and third trimesters at the study clinic. At each visit, researchers will check how much heat the participant has been exposed to using the data from the device and from her own answers to a simple questionnaire. The questionnaire will have questions about their heat exposure at work, home, type of clothing, and how they deal with hot weather. Serial ultrasound, blood and urine tests will be conducted so researchers can study signs of stress, hydration, and other changes in the body. A smaller group of participants will also wear a device to measure their body skin temperature, heart rate, physical activity and sleep during pregnancy.
When the baby is born, researchers will collect information about the birth, including the baby's weight and length, the time of delivery, and whether there were any complications during birth. After delivery, both the mother and baby will be followed for up to 12 months. During this time, the research team will check the health of both the mother and baby and see how heat exposure during pregnancy may affect the baby's growth over time. At delivery, placental weight and volume will be collected for a smaller group of women. Breastmilk sampling will also be done for this group of women to understand the effect of high temperatures on breastmilk quality.
This study does not involve any treatment or medicine. Instead, researchers will observe the participants to learn how real-life heat exposure affects them during pregnancy. The findings from this study may help public health officials and governments find better ways to protect pregnant women and babies from the harmful effects of climate change and extreme heat, especially in places with limited resources.
详细描述
Background
Anthropogenic climate change has led to a significant rise in global temperatures, resulting in more frequent, intense, and prolonged heat events. This has profound health implications for vulnerable populations, particularly in low-resource settings. Pregnant women are particularly susceptible, as heat exposure can disrupt maternal thermoregulation and fetal development, potentially leading to complications such as preeclampsia, gestational diabetes, hypertensive disorders, cardiovascular events, and increased risks of preterm birth, low birth weight (LBW), small-for-gestational-age (SGA) births, and stillbirths.
Studies have indicated a 1.04-fold increase in preterm birth odds per 1°C rise in temperature, with even greater risks during heatwaves. Additionally, associations have been observed between heat exposure and stillbirth, congenital anomalies, and gestational diabetes. Despite growing epidemiological evidence, there is limited data on the biological mechanisms driving these associations, particularly in low- and middle-income countries (LMICs).
Several biological pathways have been proposed to explain the impact of heat on pregnancy and birth outcomes. These include heat-induced hyperthermia in early pregnancy associated with neural tube defects. Exposure to high temperatures may lead to placental insufficiency due to altered blood flow. Chronic uteroplacental insufficiency may cause fetal hypoxia and intrauterine growth retardation (IUGR) and small for gestational age (SGA) newborns. Other heat stress-related pathways include oxidative stress, inflammatory responses, and prostaglandin-mediated change. In late pregnancy, heat exposure may induce early labor and preterm birth through release of oxytocin and prostaglandins. Increased maternal core temperature can impair fetal oxygenation and growth by redistributing blood flow away from the uterus.
Study Rationale
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
- 时间视角
- Prospective
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- Female
- 接受健康志愿者
- 是
入选标准
- •Single or multiple live pregnancy confirmed through ultrasound
- •Gestational age less than or equal to 13 weeks and 6 days at enrollment
- •At least 18 years of age
- •Permanent resident of the study district and plans to deliver within the district
- •Willing and able to attend study clinic visits and comply with study procedures throughout pregnancy
排除标准
- •Plan to relocate outside the district for more than 3 months during the study period
结局指标
主要结局
Incidence of Low birthweight (LBW)
时间窗: Within 48 hours of birth
Defined as birth weight less than 2,500 grams (5.5 pounds). Newborn weight will be measured within 48 hours of birth using a calibrated Seca 354 infant weighing scale, precise to 0.1 kg. Measurements will be taken independently by two trained anthropometrists. If the difference exceeds 0.05 kg, a third measurement will be taken. Quality assurance procedures and calibration protocols aligned with INTERGROWTH-21st standards will be followed. LBW will be analyzed as a binary outcome (Yes/No) to assess its association with prenatal heat stress exposure across different gestational windows.
Incidence of Small Vulnerable Newborns (SVN) births
时间窗: At the time of delivery
All live newborns who are either preterm, Small for Gestational Age (SGA), or Low Birth Weight (LBW)
次要结局
- Incidence of Pre-term birth(At the time of delivery)
- Incidence of Gestational Diabetes Mellitus (GDM)(From enrollment till birth)
- Incidence of Miscarriage(From enrollment till 22 completed weeks of gestation)
- Incidence of Gestational Hypertension(From 20 weeks of gestation till birth)
- Incidence of Small for Gestational Age (SGA)(At the time of delivery)
- Incidence of Stillbirth(From 22 weeks of gestation till birth)
- Incidence of Composite Maternal Morbidity and Mortality (CMMM)(From enrollment till 6 weeks after birth)
- Composite adverse pregnancy outcomes for the newborn(From enrollment till 7 days after birth)
- Incidence of Congenital Fetal Anomalies(From enrollment till birth)
研究者
Dr Jai Kumar Das
Doctor
Aga Khan University