Python - add 3 months to datetime

# Two methods to get new date
#  1. after 90 days
#  2. after 3 months

#---------------------------------------------------------------
# 1. after 90 days
#---------------------------------------------------------------

import datetime

range_90_days = datetime.timedelta(days=90)

date1 = datetime.datetime.strptime('09.10.2016', "%d.%m.%Y")
date2 = date1 + range_90_days
date3 = date2 + range_90_days
date4 = date3 + range_90_days

print(date1.strftime("%d.%m.%Y"))
print(date2.strftime("%d.%m.%Y"))
print(date3.strftime("%d.%m.%Y"))
print(date4.strftime("%d.%m.%Y"))
print('-----')

# 09.10.2016
# 07.01.2017
# 07.04.2017
# 06.07.2017

#---------------------------------------------------------------
# 2. after 3 months
#---------------------------------------------------------------

import datetime

date1 = datetime.datetime.strptime('09.10.2016', "%d.%m.%Y")

year = date1.year
month = date1.month
month += 3
if month > 12:
    month -= 12
    year += 1

date2 = date1.replace(month=month, year=year)

year = date2.year
month = date2.month
month += 3
if month > 12:
    month -= 12
    year += 1

date3 = date2.replace(month=month, year=year)

year = date3.year
month = date3.month
month += 3
if month > 12:
    month -= 12
    year += 1

date4 = date3.replace(month=month, year=year)

print(date1.strftime("%d.%m.%Y"))
print(date2.strftime("%d.%m.%Y"))
print(date3.strftime("%d.%m.%Y"))
print(date4.strftime("%d.%m.%Y"))
print('-----')

# 09.10.2016
# 09.01.2017
# 09.04.2017
# 09.07.2017