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Factors Affecting Natural Conception

There are a number of factors that affect the chances of successful Fertilisation of the Sperm and Egg (Conception).  This section will outline some of the main Barriers to successful conception and the next Section will outline ways you can help overcome these Barriers.

Use of Contraception

If you’ve been using hormonal contraceptives (e.g., birth control pills, intrauterine devices) or other forms of contraception, it may take some time for your menstrual cycle and fertility to return to normal after discontinuation.


Age plays a big factor in conceiving successfully and also having a successful Pregnancy.  The ability for a women to conceive decreases gradually beginning about 32 years and decreases more rapidly after 37 years. Not only are the number of eggs affected but also the quality of the eggs.

Number of Eggs

There are approximately 6-7 million eggs in a female when they are at 20 weeks of gestation as a fetus themselves.  This will reduce to 1-2 million eggs at birth then to 300-50000 eggs at puberty, 25000 eggs at 37 years and 1000 at age 51 which is the average age of menopause.

Quality of Eggs 

As a woman ages the ratio of poorer quality eggs will increase compared with good quality eggs.   A good quality egg means that it has more chance of fertilising, developing into an embryo, implanting into the uterus lining and resulting in a successful pregnancy.   A good quality egg will be chromosomally “normal” (euploid) compare with a chromosomally “abnormal” (aneuploid).   This is also a reason why chance of miscarriage is higher in an older woman.

Along with these changes in the eggs there will be an increase in circulating hormone of Follicle Stimulating Hormone (FSH) and decrease in Anti Mullerian Hormone (AMH) which are measurements that can be taken with blood tests by a Fertility Specialist to indicate the status of a womens eggs.

Health, Lifestyle & Environmental Factors Affecting Fertility

General health and lifestyle choices play a significant role in conception for both the male and female. Being in Bad Health can negatively impact the health and quality of your eggs and also the mans sperm.   Maintaining a healthy weight, eating a balanced diet, getting regular exercise, managing stress, and avoiding excessive caffeine and alcohol consumption can positively impact fertility.  Environmental Factors such as exposure to certain environmental toxins, chemicals, or radiation can also negatively impact fertility. Minimizing exposure to these factors can be beneficial.

  • Access the ‘Holistic Fertility Guidebook’ in this APP written by Holistic Nutritionist Marie Belin which will give you all the tips to help boost your fertility through lifestyle and nutrition as well as how to remove potential toxins in the Environment.
  • Try our Workouts and Clean Healthy Recipes for Fertility Boosting.
  • There are also supplements available that can help with improving both the womans and males fertility health – speak to a Fertility specialist to recommend the best ones for you.

Underlying Medical Conditions Affecting Male & Female Fertility

The embryo will be made up of 50% Male Chromosomes and 50% Female Chromosomes so the contribution is equally as important.  There are a number of medical conditions that can affect both Females and Males female fertility.

If you know you have any of the below conditions it is worth seeing a Fertility Specialist early on in your Fertility journey to help manage and treat any medical conditions improving Fertility and your chance of Success.  If you have been trying for a while with no success a Fertility Specialist can help screen for some of the below conditions to see if they are causing issues for you.

Difficulty with Ovulating

An egg needs to be released from its follicle within the ovary through ovulation in order to give a chance to be fertilised by the sperm.  In some women they do not ovulate every cycle and for some women they may need help with ovulation.  You will not be able to tell yourself whether an egg has been released or not during Ovulation therefore we advise having the Fertility Assessment where the specialist will be able to check whether you have any issues with ovulation and then can advise and treat accordingly.

Having Sexual Intercourse at the Right Time - In the Fertile Window

Timing is critical for conception. Pregnancy is most likely to occur if sexual intercourse takes place during the fertile window, which is typically around the time of ovulation. Ovulation occurs in the middle of the menstrual cycle, usually around day 14 (14 days after 1st day of your last period) but it can vary from person to person. Tracking menstrual cycles and using ovulation prediction kits can help identify this fertile period.  Read more about ways you can track your fertile window in the next Section.  If you have very irregular menstrual cycles or long periods of time between your menstrual cycles we recommend seeing a Fertility Specialist who can help regulate your periods.

Implantation Issues

If one of the Eggs has successfully fertilised and grown into an Blastocyst (Embryo) it can only continue developing if it implants successfully into your Uterine Lining.  There are a number of reasons that Implantation does not happen.  A few include:

  • Uterine Health – to help chances of implantation the uterus lining needs to have built up to approximately 7-12mm thick and show a triple line pattern – if there are abnormal growths in the Uterine lining such as Polyps or Fibroids these can in some cases affect implantation
  • Endometrial Receptivity Window – there is a small window of time (4-5) days where the endometrium cells within the uterus lining are receptive to the embryo implanting – outside of this window the endometrium of the uterus lining will block the embryo from implanting
  • Embryo Factors – The Embryo is not of good quality or chromosomally abnormal it may not implant
  • Immune System – there can be factors in the immune system that prevent implantation

Barriers to the Sperm Reaching the Egg

Ejaculation of sperm needs to happen into the vagina and if their are issues on the male side with having an erection or ejaculation or on the female side where it is too painful to allow penetration then these issues need to be addressed which we cover in the next section.

The ability of sperm to reach the eggs depends on sperm count, their ability to move and their morphology (look of the head and tail).  The sperms role is equally important towards successful conception and depends on sperm count, motility, and morphology.  Even though millions will be ejaculated only hundreds will make the journey due to some coming up against barriers in the womans body and some not having the ability to swim or dying on the way.

Barriers in the womans body that can affect the sperm can include:

  • Too much acidity around the vagina and cervix can weaken and kill sperm – lowered level of acidity allows the sperm which are more alkaline to survive and move into the fallopian tube – you can find over the counter vaginal PH tests to check
  • Antisperm antibodies may be be present in the sperm serum or in the cervical mucus can weaken or kill sperm
  • Elevated immune response from the female to foreign bodies entering the body including sperm

Issues with the Sperm

Just like the Eggs needing to be of good quality the same applies to the Sperm.

  • At least 50% of the sperm in the semen being ejaculated needs to be healthyThere needs to be enough healthy ones in the semen being ejaculated.  T
  • They need to look a certain way (ie. one head and one tail) with not double heads, crooked tails.
  • They need to be able to swim well
  • Their genetics need to be normal without chromosomal issues

The table below outlines different issues that can affect the capability of the Sperm to fertilise

See Our Next Section with Advice and Recommendations on Ways You can Address These Barriers

Vaginal PH – How to Keep a Healthy Balance –,tubes%20to%20fertilise%20an%20egg.

American College of Obstetricians and Gynecologists Committee on Gynecologic Practice and Practice Committee (2014), 101 (3) Fertil Steril

Menge et al (1982) The incidence and influence of antisperm antibodies in infertile human couples on sperm-cervical mucus interactions and subsequent infertility. Fertility and Sterility. Vol 34. No.4.

Lindsay TJ, Vitrikas KR. Evaluation and treatment of infertility. Am Fam Physician. 2015 Mar 1;91(5):308-14

Philips et al (2023) Infertility: Evaluation and Management, Am Fam Physician, Vol 106, No. 6

La Vignera S, Vita R. Thyroid dysfunction and semen quality. Int J Immunopathol Pharmacol. 2018 Jan-Dec, 32

Łakoma K, Kukharuk O, Śliż D. The Influence of Metabolic Factors and Diet on Fertility. Nutrients. 2023 Feb 27;15(5):1180

Hull SC, Kass NE. Adults with cystic fibrosis and (in)fertility: how has the health care system responded? J Androl. 2000 Nov-Dec;21(6):809-13

Miller D (2018) The Epic Journey of Sperm through the Female Reproductive Tract, Animal 2018 12 (Suppl 1), 110-120

Fodina et al (2021) Reasons and Mechanisms of Recurrent Failed Implantation in IVF. Infertility and Assisted Reproduction.

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