Subfertility is defined as the incapacity to achieve a clinical pregnancy after 12 months of “normal unprotected coitus.” When referring to ‘normal coitus”, the frequency should be taken into account and its temporal relation with ovulation.
Insofar as frequency, it has been proven that the accumulated probability of one year for pregnancy increases when there are at least two coital relations per week (Table 1). (1) (2)
|Woman´s Age||Coitus 2/week||Coitus 1/week|
|19 to 26 years old||8%||15%|
|27 to 34 years old||13-14%||22-24%|
|35 to 39 years old||18%||29%|
Table 1. Probability of no pregnancy after 12 months of exposure according to the woman’s age and weekly coital frequency.xposición según la edad de la mujer y frecuencia coital-semana
In reference to the moment, it has been documented that incorrect programming of coital relations as referred to the woman’s fertile days during the menstrual cycle, affects the probability of pregnancy. Fertile days in which unprotected coitus may result in conception is known as the “fertility window.” Although there is consensus in which the fertility window closes on the day of ovulation, its start and therefore its duration vary between couples with a range between <1 to >5 days. The duration of the fertility window is directly related to the probability of pregnancy.(3)
“Programmed coitus” is based on the ability to detect in a prospective manner this fertility window and thus maximize the probability of conception. (4)The majority of women ovulate 14 days before the onset of the first day of menstrual flow. However, due to the fact that there is a large variation in the duration of menstrual cycles (counted from the first day of menstrual flow until the day before the following menstruation) between women and even in the same woman, the sole utilization of the menstrual cycle can be a very unreliable method to predict ovulation.
The transvaginal ultrasound performed by trained clinical personnel is the standard of reference to establish the moment of ovulation. However, there are practical and economical home methods that can predict the fertile period in a large percentage of women.
Among these are the levels measured through urine of hormones such as the luteinizing hormone (LH) and estrogens, the tracking of basal body temperature and the evaluation of cervical mucus and saliva.
It is important to review the pros and cons of each of these methods and available devices in the marketplace used for measuring these levels in those women who iniate their pursuit of pregnancy so that they may have more probability of achieving conception in an effective manner.
The popularity of applications on the web that detect fertile days based on software for use on a “Smartphone” is increasing. Although the majority of these applications are only based on the duration of menstrual cycles and the date of the last menstruation, there already exist some which incorporate hormonal analysis, and/or tracking of body temperature. (5)
Existen diferentes alternativas complementarias que ayudan a predecir la ventana y el pico máximo de fertilidad además de la longitud y duración de los ciclos menstruales con aplicativos basados en la web. La información guardada a través de estas aplicaciones puede asistir en el manejo médico de las pacientes que desean un embarazo. La no detección de ovulación por tres meses consecutivos o un fallo en la concepción después de 6 meses de coito programado a través de aplicaciones que detectan objetivamente la ventana de fertilidad puede ser una indicación para agilizar el proceso de estudio de una mujer y su pareja