The inability to conceive a second time after a prior successful pregnancy can be confusing and frustrating for couples. This experience is formally known as secondary infertility, a common challenge for those trying to grow their family. Understanding the biological, lifestyle, and time-related shifts that have occurred since the first child was born is the starting point for finding answers.
What Is Secondary Infertility?
Secondary infertility is defined as the inability to become pregnant or carry a baby to term after having successfully done so in the past without fertility treatments. This is distinct from primary infertility, which describes a couple that has never achieved a pregnancy. The previous successful birth does not grant immunity from future fertility issues, as the body and circumstances of both partners change over time.
This condition affects approximately 11% of couples in the United States. Medical professionals typically suggest an evaluation if a couple has been trying to conceive through regular, unprotected intercourse for 12 months if the female partner is under 35 years old. That timeline shortens to six months if the female partner is 35 or older, reflecting the impact of advancing age.
Changes in the Mother’s Body Since the First Pregnancy
One significant factor contributing to secondary infertility is advancing maternal age. Women are born with all the eggs they will ever have, and their quantity and quality naturally diminish over the years. Even a few years between pregnancies can mean a noticeable decline in ovarian reserve and an increase in eggs with chromosomal abnormalities, which raises the risk of miscarriage.
Changes to the reproductive organs can occur as a result of the previous pregnancy or delivery. Scarring in the uterus, sometimes called isthmocele, can develop from a prior Cesarean section (C-section) or a procedure like a dilation and curettage (D&C). This scar tissue can interfere with the implantation of an embryo into the uterine lining. Infections or conditions like pelvic inflammatory disease (PID) can also lead to blockages or damage in the fallopian tubes, preventing the egg and sperm from meeting.
New endocrine and hormonal issues can disrupt the ovulation process. Conditions such as polycystic ovary syndrome (PCOS), which causes irregular ovulation, may develop or worsen over time. New thyroid disorders or premature ovarian insufficiency (where the ovaries stop functioning fully before age 40) can also emerge, impacting the hormonal balance necessary for conception.
Significant changes in body weight since the first pregnancy can also affect conception. Both substantial weight gain (which disrupts reproductive hormone levels and causes ovarian dysfunction) and excessive weight loss can interfere with the regular release of an egg. These changes alter the hormonal signaling that governs the menstrual cycle and ovulation, making conception less likely.
Factors Affecting the Partner and Lifestyle
While attention often focuses on the female partner, male factor changes account for approximately one-third of secondary infertility cases. The male partner’s age plays a role, with a decline in semen quality and quantity typically seen after age 40. Aging can also affect the integrity of the sperm’s DNA, which may increase the risk of miscarriage or problems with embryo development.
The quality of sperm can be affected by new health conditions or external influences. New medical diagnoses, such as diabetes or hypertension, or starting new medications can impact sperm production and testosterone levels. Exposure to environmental factors like excessive heat (common in certain occupations) or new exposure to toxins can also diminish sperm health.
A man who was previously subfertile may face issues now that his partner’s egg quality has declined. Conditions like a varicocele (enlarged veins in the scrotum that raise testicular temperature) may have been present before but create a more significant problem when combined with the female partner’s advancing age. Therefore, a current semen analysis is an important step, regardless of past success.
Lifestyle shifts affecting both partners can decrease the chance of conception. Increased stress, changes in diet, or the use of tobacco and alcohol can negatively influence the quality of both eggs and sperm. The demands of parenting a young child often lead to a reduction in the frequency of intercourse. This change in timing can mean that opportunities to conceive during the woman’s fertile window are missed.
The Diagnostic Pathway
The initial step in addressing secondary infertility is a detailed consultation with a healthcare provider or fertility specialist. The doctor will conduct a comprehensive review of both partners’ medical histories, focusing on the first pregnancy, subsequent surgical procedures, and lifestyle changes. This history-taking is designed to pinpoint factors that may have changed since the last successful conception.
Standard testing for the female partner typically begins with blood work to evaluate hormone levels. These tests measure hormones such as Follicle-Stimulating Hormone (FSH), Anti-Müllerian Hormone (AMH) to assess ovarian reserve, and progesterone to confirm ovulation. Imaging is also performed, including a transvaginal ultrasound to visualize the ovaries and uterus, checking for conditions like fibroids or cysts.
A specialized X-ray procedure called a hysterosalpingogram (HSG) is used to assess the structural health of the reproductive tract. This test involves injecting a dye through the cervix and into the uterus to confirm whether the fallopian tubes are open and to check the uterine cavity for scarring or abnormalities. For the male partner, a semen analysis evaluates the current count, movement (motility), and shape (morphology) of the sperm.
Once the cause of secondary infertility is identified, treatment options are tailored to the specific diagnosis. For hormonal issues, medication can be used to induce or regulate ovulation. If minor structural issues or mild male factor issues are found, the couple may proceed with intrauterine insemination (IUI). For more complex diagnoses, such as blocked fallopian tubes or significant sperm issues, the physician may recommend in vitro fertilization (IVF).