Vascular Responses to UV Exposure in Pregnancy

Summary

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.

Conditions

• Pregnancy

Interventions

RADIATION

UVA radiation

20 minutes of low dose UVA from a phototherapy unit

RADIATION

Sham Control

20 minutes of sham control exposure

Sponsors & Collaborators

• NHS Lothian

  collaborator OTHER_GOV

• University of Edinburgh

  lead OTHER

Principal Investigators

• SARAH STOCK, BSc MBChB · QUEEN'S MEDICAL RESEARCH INSTITUTE

Study Design

Allocation

NON_RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

SINGLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

45 Years

Sex

FEMALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2015-09-01

Primary Completion

2016-03-31

Completion

2016-03-31

Countries

• United Kingdom

Study Locations