Ask what the approximate delivery date (SDD) puts women's consultation in which you observed. Even if you have your own opinion on this matter, send to the decree you will be according a gynecologist. Usually doctors rely on data on the timing obtained during the early fetal ultrasound. Some calculate the arithmetic mean time between the date of birth and all carried out the ultrasound studies.
Calculate your maternity leave: according to the Labour code of the Russian Federation, the period of leave with singleton pregnancy and normal childbirth last is 140 calendar days (70 days before birth and 70 days after). In the case of complicated birth - 156 days (70 before and 86 days after birth). Multiple pregnancy and birth of two and more children - 194 days (birth up to 84 calendar days and after childbirth - 110 days).
Remember, maternity leave is calculated in total, includes the period before and after delivery, and provided in accordance with the law fully, no matter how many days were "spent" before the birth.
Remember that you have the right to issue entitlement regular annual paid leave and use it immediately before maternity leave or after it.
Note that even if your plans include access to maternity leave after the deadline, the doctor has no right to give you a leaflet on disability later. In the same situation is the accountant of the employer, which does not have the right not to consider sick leave. So officially you step out in the decree within the period prescribed by law. Some employers go "to meet" and offer special conditions. But remember that the responsibility for their own health and the health of your child lies with you.
Remember that at the time of your stay on maternity leave you are entitled to benefits set by law. Benefits shall be calculated in accordance with average earnings, calculated over the 2 calendar years preceding the year of onset of pregnancy leave and maternity leave, leave to care for a child. The amount of the benefit cannot be less than the minimum wage.