After having a child, why can I get pregnant a second time?

Secondary Infertility, what is it?

“Infertility” is, in general terms, the inability to get pregnant after a year of searching and with a frequency of sexual intercourse of at least 2-3 times a week.

The surname “secondary” refers to the situation of having one child previously and not being able to achieve a new pregnancy. Unlike the “Primary Infertility” which implies not having achieved it.

The average prevalence in developed countries is estimated to be 8%.

What causes secondary infertility?

It has different causes and, in many cases, primary and secondary shares them.  

Frequent causes, common in both are:

1. Woman’s age: frequently, and due to the sociological changes in recent decades, it is the most frequent and transcendent limiting condition.

The search for first and subsequent pregnancies is increasingly delayed. After the age of 35, there is greater difficulty in achieving pregnancy and, in addition, there is a greater number of abortions. This situation is accentuated after the age of 40.

The delay in considering a first pregnancy or a new pregnancy increases the difficulty of achieving it. The ovarian reserve is closely related to age and the ovary is an organ with a short “reproductive life expectancy”.

2. Male factors (affect sperm quality): reproductive aging also occurs in men, but is later on and may vary case by case.

3. Life style: habits or behaviours affecting general health also affect fertility, both in men and women. Weight problems, especially obesity and extreme thinness, tobacco and / or alcohol, exposure to toxins and environmental chemicals. The percentage of the general population exposed is high but, in many cases, they are factors that can be corrected. Healthy life style help to have a higher chance of pregnancy.

4. Poorly controlled chronic diseases such as diabetes, thyroid disorders, and other endocrine disorders.

5. General medical or surgical interventions: drugs use affecting the ovary function or testicle (for example, chemotherapy for oncological disease), abdominal or pelvic surgeries, infections that affect internal genitalia. 

Causes occurring after the previous pregnancy:

1. Complications in previous pregnancy: infections or surgeries that have damaged the uterus, fallopian tubes or ovaries. For example, complicated caesarean sections.
2. Partner change: at present, is a frequent situation and a cause to take into account.

When should be consulted with a specialist?

When to start testing will depend primarily on:

• The woman’s age and search time. In general, in women up to 35 years old and without any other associated factor, after 1 year. In women over 40, it is recommended to start the study as soon as possible, without delay. Between 36 to 39 years, if there is no other known impairment, approximately 6 months. 

• Other medical history data we know is associated with a lower probability of achieving an evolutive pregnancy, such as those specified in the previous section, the advice is to consult it when deciding to seek a new pregnancy. 

Is important to note that there are couples who had no difficulty getting pregnant previously, but the passage of time is a determining factor for ovarian reserve.

As general advice, if you have any doubts, is very convenient to carry out a preconception consultation, to evaluate the current state of the couple.

Bibliography

• Manual de la buena práctica clínica en reproducción asistida. Grupo de interés de Ética y Buena Práctica de la Sociedad Española de Fertilidad (SEF). 2016.
• Libro Blanco. “La infertilidad en España: Situación actual y Perspectivas”. SEF 2020.
• Guía de Asistencia Práctica. Estudio de la pareja con disfunción reproductiva. Prog Obstet Ginecol. 2017:60(3):267-273.
• Epidemiología de la esterilidad. Influencia de los factores ambientales. Vicente López Villaverde. Rev. Iberoam. Fert Rep Hum, 2014; 31; 31-37.

Dr Lydia Luque, Gynecologist at Instituto Bernabeu.