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.
For paid maternity EI benefits the earliest is 8 weeks before your due date (@bipanie I thought your were referring to maternity EI). You can however take 17 weeks of unpaid maternity leave at any point I believe. Reply Like 2.