UVA Irradiation of Skin in Pregnant Women Increases Uterine Artery Blood Flow and Reduces Blood Flow Through a Nitric Oxide Pathway
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 19
- 试验地点
- 2
- 主要终点
- Uterine artery Doppler
研究概览
简要总结
Season of birth influences pregnancy for reasons that remain unclear however the answer may lie in the amount of sunshine pregnant women are exposed to. Sunshine, or ultraviolet light (UV) exposure is already known to have benefits for health on heart disease, strokes and depression. In pregnancy, relationships between sunshine exposure are evident in birth weight, preterm birth and risk of blood pressure complications. Vitamin D, the UV generated hormone, was thought to be responsible when low vitamin D levels were associated with these pregnancy complications. However, vitamin D replacement is ineffective at preventing these outcomes, and the investigators hypothesise that this is because it is the UV that is beneficial for pregnancy and it is working through a different pathway.
A new understanding of skin function is central to this, with a 2014 study showing that exposing an adult to 20 minutes of low dose UV light lowered their blood pressure and improved blood flow. These investigators demonstrated this was a direct effect of UV on the skin and was mediated by nitric oxide, a chemical central to many aspects of pregnancy including blood pressure regulation and uterine activity.
The investigators in this study have funding from Tommy's to investigate if a similar effect is seen in pregnancy on the circulation. The design is similar to the previously successful method and volunteers would be recruited from clinical areas during the second trimester. As both resting and warming for 20 minutes have the potential to have similar effects on the circulation, a control arm will expose participants to these without the UV.
This pilot study would involve one visit and measurements taken would include heart rate, blood pressure, arteriography, ultrasound of the uterine arteries and blood measurements of nitric oxide levels. Arteriography is performed using a specialised arm cuff and is safe and non-invasive. A subset of these women would be invited to repeat this in the third trimester to investigate for a difference in effect at a later gestation.
详细描述
The hypothesis is that ultraviolet A (UVA) exposure during pregnancy will release nitric oxide (NO) from the skin and that in turn this will cause blood vessel dilatation. This will be seen by changes in uterine artery blood flow, blood pressure, and arterial stiffness (arteriography). The aim is to investigate this in a low risk group and a high risk group, as these 2 groups of women have different baseline characteristics of their vascular system and potentially different responses to our intervention. A subset of these women will be invited to repeat the intervention in the third trimesters of their pregnancies to establish if the effect differs with advancing gestation. Birth outcomes on participants will be collected to check if the high and low risk groups are representative of this status.
Participant contact information will be kept separately from their collected data to anonymise the collected data and all outcome data will be de-identified. All collected information will be stored on secure university servers that are password protected.
Participants will be recruited to participate in the low sunshine months November 1st until March 1st to minimise background sunshine and UV exposure.
LOW RISK ARM:
20 participants will be recruited from community and hospital antenatal clinics, day assessment unit, labour ward or at first trimester screen appointment by posters, a research midwife or a member of clinical research team. Potential participants will be given an information form and will be asked to give written consent following sufficient time for consideration.
研究设计
- 研究类型
- Interventional
- 分配方式
- Non Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- Single (Investigator)
入排标准
- 年龄范围
- 18 Years 至 45 Years（Adult）
- 性别
- Female
- 接受健康志愿者
- 是
入选标准
- •Pregnant volunteers
- •Ages 18- - 45
- •No significant medical or obstetric history
- •English speaking
- •Able to provide informed consent
- •Singleton pregnancy
- •Low risk first trimester screen
- •Have 4 hours of time
- •Historical risk factors for growth restriction or pre-eclampsia
- •Papp A < 0.40 MoMs
- •Exclusion criteria:
- •Non english speaking
- •History of intrauterine growth restriction (IUGR) or pre-eclampsia
- •Contraindication to UV exposure
- •History of blood born viruses (hepatitis B, C, HIV)
排除标准
- 未提供
结局指标
主要结局
Uterine artery Doppler
时间窗: Change over 60 minutes following exposure
The uterine artery will be interrogated with abdominal ultrasound to determine diameter and Doppler measurements to calculate resistance indices (PI) and flow velocity. This will be done at baseline and at 10 minutely intervals following exposure for 60 minutes.
次要结局
- Arteriography(60 minutes)
- Blood pressure(60 minutes)
- Nitrospecies(60 minutes)