Calculating the days most likely to get pregnant

Know the dates you are more likely to achieve conception is a major consultations for women who want to become pregnant. Through simple calculators you can get a good idea about the days of ovulation and the most favorable for pregnancy. These tools are the result of a calculation based on the method of Ogino-Knaus, a tool for family planning to the World Health Organization attributed 75% efficiency.

However, a study published in the British Medical Journal reports that the margin of error of this method to calculate the most fertile day could be higher. After analyzing the cycles and ovulation days over two hundred and twenty women, the authors concluded that the system only succeeds in calculating fertile day of 30% of them. This may be because, according to various reports, nearly half of the Spanish mistakenly identifies the best time to get pregnant. And a quarter of them ignored which days are the most fertile cycle.

The key to the design is at the date of ovulation, the day the egg is released from the ovary and is picked up by the fallopian tubes, which is the most fertile. However, as the egg can be fertilized for up to 48 hours later and the male sperm can survive several days in the female body, the fertility cycle is extended from four to five days before ovulation to one or two days later. Ovulation usually occurs between 12 and 16 days before the next menstruation. In a regular 28 day cycle usually coincides with the 14th, while for women with shorter menstrual cycle ovulation date is advanced (day 12 or 13). Similarly, for longer cycles, delayed (day 15 or 16). To make the calculation is only necessary to know the date of the last menstrual period and cycle length.

On the Internet there are several calculators:

Fertile days: This calculator fertility estimates based on the start date and duration of both the cycle and the luteal phase (time between ovulation and the onset of the next menstruation). After entering this information, a schedule is obtained with the six most fertile days of the cycle, with indications on medium-high, high fertility and ovulation, with maximum fertility.

Fertilab: This is a comprehensive fertility calculator. Apart from its date of last menstrual cycle, a woman must indicate the weight, age and height. The result is six calendar with upcoming dates of ovulation, estimating the following rule, days to prevent pregnancy and the probable date of birth if the pregnancy is achieved. It also provides information on the ideal weight for women before pregnancy and the relationship with the current weight.

Fertility calculator of  Instituto Bernabeu: Ovulation Calculator This assisted reproduction center allows for greater accuracy in the results, to enable women indicated, and the dates of your last cycle, the penultimate and ante-penultimate period.

Pregnancy and Fertility: With the introduction of the data of the last period and the approximate length of menstrual cycles, this tool calculates the fertile days, fertile and the likelihood of implantation of the fertilized egg.