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Date of issue: January 2019, Version: 2.1

The major component of natural gas is methane; minor components include short chain aliphatic hydrocarbons such as ethane, propane and butane.

Natural gas is pharmacologically inert but at concentrations greater than 80% may produce asphyxia and possibly central nervous system depression.

No studies have been located concerning the fetal effects of maternal natural gas poisoning in pregnancy. The highly limited human pregnancy exposure data which are currently available consist of two small studies investigating pregnancy and infant outcomes among women who lived in a home with gas cookers during pregnancy, with no documented evidence of natural gas poisoning. No evidence of increased risks of low birth weight, small for gestational age or first year childhood illness was provided from these studies.

Additional studies are available which have investigated pregnancy outcomes following maternal residence close to areas where natural gas is developed through unconventional extraction methods (hydraulic fracturing/fracking). Although these studies have provided inconsistent and conflicting evidence of associations with adverse pregnancy outcomes, these data are likely to be highly confounded. The results of these studies are also considered highly limited in their ability to predict risks of adverse pregnancy outcomes following exposure to purified natural gas in typical domestic/occupational settings and should not be extrapolated.

Following exposure to natural gas in a pregnant patient, maternal toxicity is likely to be a major determinant of risk to the fetus. However, due to a lack of data concerning the teratogenicity of natural gas, it is not currently possible to state that an absence of maternal toxicity excludes the possibility of adverse events occurring in the developing fetus.

Enhanced fetal monitoring may be warranted and should be decided on a case-by-case basis. Discussion with UKTIS is recommended in all cases where domestic/natural gas poisoning has occurred.

This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to NHS health care professionals who are logged in.

If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.

If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.

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