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Secondary Infertility, Common Causes, and the Connection with Postnatal Depletion

Updated: Jan 31

Secondary infertility is defined as the inability to become pregnant or carry a pregnancy to a live birth following a previous successful pregnancy. Did you know that it is more common than primary infertility?

Some interesting statistics from a Health Masters Live masterclass I attended on unexplained infertility with Australian Naturopath Angela Hywood confirmed:

1.7% of women suffer from primary infertility

10.5% of women with at least one live birth suffer from secondary infertility.

Secondary infertility can be a frustrating journey especially if you didn’t have any problems conceiving your first child. You may be wondering what has happened to you and whether the birth of your first child has broken you.

This was me. My first son was born in 2008 after a healthy problem free pregnancy. He was conceived fairly easily. His birth though was not so easy. I will share a little about this later.

Despite deciding to try again in early 2009 when he was just over 12 months old, it took me nearly 10 years to finally have a second child. My beautiful baby girl was born in early 2019.

The guilt and the blame

Even though secondary infertility is much more common than primary fertility, in society it is often not seen to be as big of an issue as you already have a child. We are often told that we should be grateful that we have one child as many people in the world aren’t even able to have one.

While I did feel grateful and totally blessed to have a son, I also felt angry at myself for not being able to get pregnant, I blamed myself for being broken and felt guilty that I was unable to give my son a sibling to play with. He would often ask in his preschool and primary years “why don’t I have a brother or sister?” or “when will I be getting a brother or sister?” I felt so bad for him, especially when all of his friends one by one started getting their own brothers and sisters, and some even went on to have a second sibling as well.

It was tough for me too when my son was young as I was also in a mother’s group where the talk was all about babies and every single one of them went on to have a second child. With secondary infertility, you are faced with the pain and reminders daily as you are unable to hide from or block out babies and pregnancy because of the life stage you are already in with a toddler or preschooler. Soon I was the only one out of absolutely everyone I knew in my circle who didn’t at that time have a second or third child.

What are the causes?

There can be many causes of secondary infertility and in many cases, a cause may not be found and you are categorised as unexplained. These are some of the common causes which are investigated by your doctor and fertility clinic:

Egg quality and quantity

The quality and quantity of your egg supply are related to age and many women are having children later in life. If you are over the age of 35 your chances of conceiving each cycle are naturally on the decline.

Structural issues

This could be scar tissue or damaged or blocked fallopian tubes. If any of these issues are suspected you will most likely have a scan at the hospital where they will filter a blue dye through your fallopian tubes to check for blockages.


You may have always had some mild endometriosis which didn’t affect your ability to have a first child but may have worsened over time and is a problem now. Endometriosis is common and is where uterine tissue grows outside the uterus in locations such as the ovaries, fallopian tubes, or other organs such as the bowel. Depending on the severity of the endometriosis the inflammation and scar tissue can lead to issues with egg quality, ovulation, and implantation.


Uterine conditions such as fibroids may be present and are connected to estrogen dominance and are common in women over the age of 35. Fibroids can occur in 7 out of 10 women by the time they reach 50.

Hormone Imbalances

Common hormone imbalances that can affect secondary infertility are estrogen dominance, low progesterone, low or excess androgens as well as issues with low or excess cortisol from your adrenal glands. These issues may not always be picked up by the standard day 5 or 21 blood test you have with your doctor.

We are very fortunate these days to be able to investigate hormones on a deeper level with a dried urine test called the DUTCH test. The DUTCH test offers a comprehensive hormone test that includes hormone metabolites, organic acids, and methylation and oxidative stress markers. It is especially useful for investigating adrenal function, estrogen and progesterone balance, androgen deficiency or excess, and whether the metabolism of hormones is sluggish or overactive. I can organise a DUTCH test for my clients and I am trained to be able to interpret the results, which can seem quite complex when you first look at them as there is so much valuable information. The DUTCH test is a great way to investigate what is really happening with your hormones as it not only provides information on free hormones but downstream metabolites as well which tells us how the hormones are functioning.

Thyroid health

It is quite common to develop thyroid issues in the postpartum period after having your first child and for many the changes in metabolism are permanent. I will talk more about this later in this blog.

Autoimmune conditions

In some cases, pregnancy can trigger the onset of many autoimmune conditions, examples of these might be Antiphospholipid Syndrome, Lupus, Hashimoto's Thyroiditis, Graves Disease, and Rheumatoid Arthritis. `Research has shown that autoimmune diseases have a significant prevalence within the female population and a considerable portion of women who are mothers. 44.3% of women who develop an autoimmune disease have onset after the first year of pregnancy (1)

There are many theories why this occurs such as fetal cells remaining in the mother postpartum and triggering an autoimmune response as well as the stress and demands of pregnancy, hormone imbalances, and cesarean delivery (which increases the risk).

There are more than 70 registered autoimmune conditions and many of these can go unnoticed and undiagnosed. In the case of recurring miscarriages, your doctor may test you for antinuclear antibodies (ANA) to see if you have elevated autoantibodies attacking your body tissues. It is also important to also get screened for antiphospholipid antibodies (to see if blood clotting is an issue), Coeliac Disease, and autoimmune thyroid disease (Hashimoto’s or Graves).


An infection of the urinary and reproductive tract called ureaplasma may be problematic with severe cases of endometriosis and recurring pregnancy loss. Ureaplasma is microscopic bacteria that colonise the urinary and reproductive tract and are for most people harmless and asymptomatic. An overgrowth though can cause inflammation of the endometrial lining and may require a course of antibiotics to resolve.

Polycystic ovary syndrome (PCOS)

PCOS is a common syndrome that can affect fertility as women with PCOS may not ovulate and may have irregular periods. Females with PCOS may have insulin resistance, high levels of androgens, excess hair growth, acne, and weight gain.

Lifestyle factors

Excessive weight gain in both males and females as well as smoking, alcohol use, and level of exercise.

Male factor

In men, common reasons are a low sperm count, a varicocele, and other sperm abnormalities.

Unexplained Secondary Infertility

If after the standard blood tests and scans with your fertility clinic nothing obvious is identified, which was the case with me, you will be labeled as “unexplained” and usually advised to go on the waiting list for IVF. Around 1 in 5 cases of secondary infertility are identified as unexplained which basically means your fertility doctor has found no obvious reason that you are unable to conceive a second child. This is not the end of the road, though because there is a whole world of further options to explore in the world of functional medicine.

Postnatal depletion

I believe postnatal depletion is a major cause of unexplained secondary infertility. Mothers are so depleted of nutrients and energy from pregnancy and breastfeeding that they are just not physically capable of conceiving again until they build themselves back up again.

Having a baby and breastfeeding is hugely demanding and can change a woman’s body forever. During pregnancy and breastfeeding the baby will strip all the nutrients it needs to grow from the mother’s nutrient stores leaving her at risk of nutritional deficiencies such as iron, calcium, vitamin B12, folate, and zinc. This nutrient depletion will impact the body’s ability to function normally and as a result, there can be changes in metabolism and hormone health. The adrenal glands in particular can become fatigued from the demands of motherhood and sleepless nights, which then impacts on the thyroid and progesterone levels. Many mothers may also be recovering from the emotional trauma of difficult birth and maybe (like I had) excessive blood loss which resulted in low levels of iron and B12 which took a while to return to healthy levels.

So, when you try and get pregnant again in this state, your body is like NO WAY!

According to Functional Medicine Doctor Oscar Serralach, Author of the book The Postnatal Depletion Cure, Postnatal depletion can affect mothers from birth until the child is 7 years of age and possibly longer. Typical symptoms of postnatal depletion are fatigue, exhaustion, brain fog, hypervigilance, loss of self-esteem, overwhelm, and a loss of libido. (2)

I believe that postnatal depletion was a huge contributing factor to my secondary infertility journey.

My story

My first son was conceived fairly easily after 5 months of trying and my pregnancy was relatively easy with no major complications. Despite my problem free pregnancy, my son’s birth was far from easy I won’t go into all the details but I can say it was a painful labour that went on for over 24 hours. He was a big baby, there were some complications, and he was finally helped out with episiotomy and ventouse as he was stuck and unable to progress for a long time.

Immediately after I gave birth to my son I has a massive postpartum hemorrhage, which required urgent medical attention at the time, an experience that was very scary. I remember the doctor, nurses, and midwife all rushing around looking a little panicky pressing on my stomach to get the placenta out and there was an awful lot of blood.

My health deteriorated the next day and doctors informed me that because my hemoglobin (protein in your red blood cells that carries oxygen throughout your body) was so low I would need an immediate blood transfusion. It was about 92 g/L when it should be no lower than 114 g/L. The normal reference range for females is 120 g/L - 160 g/L. I didn’t like the sound of a blood transfusion however, after a chat with the doctor, I realised that I would not physically have the energy to able to look after my child unless I have a blood transfusion. So I did.

My challenges didn’t end there. Maybe due to the blood transfusion, my milk supply didn’t come through and after 10 days I had to take a prescription anti-nausea drug to kick start my prolactin hormone production which is the hormone that starts off the breastfeeding process. I also had to spend a lot of time expressing and topping up with formula milk which was very stressful and meant that I didn’t spend much time sleeping.

Everything really started to take its toll in the first week after my son was born and to make matters worse I couldn’t sleep! Sleep when your baby sleeps they would say, but every time I tried to sleep my mind was wide awake. I remember being so tired that I fell asleep while sitting up and talking to the hospital canteen lady who had come to take my food order. I literally didn’t sleep for a whole week!

Looking back, I think about the huge emotional and physical toll of my son’s labour and the weeks that followed and how this would have affected my health. This is in addition to the ongoing demands of 14 months of breastfeeding when it was eventually established and 7 months of my son waking multiple times during the night.

When my son was just over 12 months, we decided to try for another baby. I didn’t feel totally ready at first and hoped that it would take several months like last time. A few weeks later I realised that my period was late and so I took a pregnancy test at what would have been nearly 5 weeks. I was shocked to see it was a faint positive and thought I would take another test the next day to make sure before saying anything to anyone only to find that my period had arrived. This was likely my first chemical pregnancy.