Getting a tan, whether in a salon or in the sun, is probably not a good idea, whether you're pregnant or not. A tan is your skin's attempt to protect itself from the damage caused by ultraviolet (UV) radiation. Exposing yourself to UV rays repeatedly, and for long periods of time, worsens the effects of ageing. It can also increase your risk of developing skin cancer. We don't know how exposure either to sunlight or to artificial UV rays affects a developing baby. Some studies suggest there may be a possible link between exposure to UV rays and mums-to-be not having enough folic acid in their bodies. This is because folic acid can be broken down by UV rays. In the first few weeks of pregnancy, high levels of folic acid can help to protect your baby from developing defects of the spinal column and brain (neural tube defects), such as spina bifida. So as a precaution, try to avoid intense or prolonged exposure to UV light around the time you conceive and in early pregnancy. You should also take folic acid supplements during your first trimester. Sunbathing If you want to spend a peaceful afternoon in the sun, you can. Just make sure you don't get too hot and that you protect your skin with sunscreen. During pregnancy, your skin may be more sensitive and you may burn more easily in the sun. If this applies to you, stay out of the sun whenever you can. Use plenty of sunscreen, too. Your skin may change colour more easily when you're pregnant. This is because during pregnancy, you have higher levels of a hormone that makes your skin react to the sun by going darker. This hormone is called melanocyte-stimulating hormone. It can cause irregular dark patches on your face (chloasma or melasma), or a line appearing down the middle of your belly (linea nigra). Sunbathing can make chloasma and linea nigra even more noticeable. It may also help to stay out of the sun during the middle of the day when it is hottest. Lying in the hot sun for hours on end increases the risk of overheating and dehydration. Neither of these is good for you or your developing baby.
http://www.babycentre.co.uk/x541041/is-it-safe-to-sunbathe-or-use-a-sunbed-during-pregnancy#ixzz2zX7atG1S