Gases that contribute to the greenhouse effect include: 1  Water vapor. 2  Carbon dioxide (CO 2). 3  Methane. 4  Nitrous oxide. 5  Chlorofluorocarbons (CFCs).
You can start maternity leave any time from 11 weeks before the beginning of the week your baby's due. You can bring the date forward if you need to take time off work for pregnancy-related reasons within four weeks of the expected birth date. Your employer may make you start your leave from then.
To claim your right to maternity leave, you must tell your employer about your pregnancy no later than 15 weeks before your baby is due. You can work this out by finding the Sunday before your baby is due, and then counting back 15 weeks.ven if you don't decide to take all of the maternity leave you're entitled to, you will have to take two weeks of leave after your baby is born. If you work in a factory you must take an extra two weeks' compulsory leave, so you'll be off work for a month.