Getting pregnant - tips with a scientific background

Once a couple decides they want children, they often want to get pregnant quickly . The good news is that, under normal circumstances, couples having regular, unprotected sex have a good chance (around 90%) of becoming pregnant within a year. (1)

This article deals with interesting facts about the female cycle, as well as tips on how to get pregnant .

Getting pregnant

A pregnancy occurs when an egg and a sperm meet. That sounds simple at first, but the timing has to be right.

Only one ovulation occurs in each cycle. The lifespan of the mature egg is approximately 12-24 hours. Fertilization is only possible within this narrow window (2). Sperm, on the other hand, have a lifespan of about five days, so the highest probability of conception through (unprotected) intercourse is in the week before ovulation until one day after.

To determine the fertile days around ovulation , it is helpful to know the phases of the female menstrual cycle.

The female cycle

Every month, the female body prepares for a possible pregnancy. This involves a precisely coordinated interplay of hormonal processes.

The length of a menstrual cycle is calculated from the first day of menstruation until the start of menstruation in the next cycle. On average, a woman's cycle lasts 28 days, although this can vary considerably from woman to woman. Longer or shorter cycles of 21 to 40 days are also normal. (5, 6)

The variability in cycle length usually results from different lengths of the first half of the cycle, the follicular phase. (1, 3-5) The menstrual cycle can be divided into two phases:

(1) the follicular or proliferative phase and

(2) the luteal or secretory phase.

Follicular phase

The follicular phase gets its name from the maturation of egg cells from the ovarian follicles in the ovary (ovary). This phase lasts between ten and 20 days and varies from woman to woman. (3)

The follicular phase begins on the first day of menstruation (i.e., the shedding of the uterine lining = menstrual bleeding) and lasts until the day of ovulation when the mature follicle is released (i.e., when the egg is released = ovulation). (5)

Characteristic of this phase are a lower waking temperature, also called basal body temperature, and a rise in follicle-stimulating hormone (FSH). FSH primarily triggers the maturation process of the follicles in the ovaries. Over time, the growing follicles produce increasing amounts of estrogen, a hormone that initiates ovulation, while the FSH level drops again.

luteal or secretory phase

Around day 14 of the cycle, the follicle ruptures and the egg is released into the fallopian tube. Most women ovulate between days 11 and 21 of their cycle. The luteal phase of the cycle is relatively constant at 14 days for all women. (6)

Estrogen plays a key role in this process, helping to prepare the body for a potential pregnancy. This hormone supports the build-up of the uterine lining and triggers the production of luteinizing hormone (LH). Furthermore, it promotes the secretion of the clear cervical mucus, which is produced in the cervical glands located in the cervix and at the opening of the uterus, and which allows sperm to enter the uterus.

The LH surge begins approximately 34 to 36 hours before ovulation and is a relatively precise indicator of the time of ovulation. Ovulation occurs approximately 10–12 hours after the LH peak. (4)

If fertilization and implantation of the egg cell in the uterus do not take place, the cycle ends on the day before the next menstrual period begins.

Determining fertile days

The fertile window typically begins about five days before ovulation and ends within 12-24 hours after ovulation. Therefore, the likelihood of becoming pregnant during menstruation is very low.

To increase the chances of pregnancy and to determine the time of ovulation, various methods can be used (6):

• Measurement of luteinizing hormone (LH)
• Measurement of basal body temperature (= lowest body temperature at rest)
• Calendar method

The hormonal changes before and after ovulation lead to noticeable and measurable physical changes. These methods can be used to identify the relatively few fertile days during the female cycle. (6, 7)

Tracking the menstrual cycle can also be used to detect and diagnose cycle disorders. Hormonal changes often lead to irregularities in the menstrual cycle, which can cause ovulation disorders. (2) However, stress, travel, or other factors can also delay or prevent ovulation.

Measurement of luteinizing hormone (LH)

During the menstrual cycle, the amount of LH in the body rises approximately 12-36 hours before ovulation. This knowledge is helpful when using ovulation tests. These tests measure the concentration of LH in a woman's urine* and can thus help determine the time of ovulation.

Temperature method

A woman's fertile window can be determined by measuring her body temperature daily. The method is based on changes in core body temperature during the menstrual cycle. In the second half of the cycle, shortly after ovulation, a higher basal body temperature (approximately 0.3°C to 0.7°C higher) can be measured than in the first half of the cycle. This temperature difference, which is most noticeable during sleep or immediately upon waking, serves as an indicator of ovulation. (3)

Calendar method

Calendar-based methods track the days of the menstrual cycle to determine the beginning and end of the fertile period. The calendar method calculates fertile days assuming ovulation occurs mid-cycle, 14 days before the next period. (6) The standard-day method involves having unprotected intercourse regularly between days 8 and 19 of the cycle when trying to conceive. Because cycle length, and therefore the day of ovulation, varies, this method is the least accurate.

Factors influencing fertility

Besides knowing one's fertile days, other factors can also influence the success of a pregnancy. These include unchangeable factors such as ovulation disorders, uterine abnormalities, and altered sperm production, as well as genetic factors and age. (8)

Furthermore, a number of lifestyle factors such as diet, obesity, smoking, intensive exercise, alcohol consumption, and stress have a negative impact on fertility . (8)

Nutrition

It is known that diet can play an important role in influencing fertility in both men* and women*. (8, 9) A healthy diet that includes healthy fats, fish, whole grains, fruits, and vegetables is associated with increased fertility in both women* and men*. A balanced ratio of proteins, carbohydrates, lipids, antioxidants, and folic acid in the daily diet contributes significantly to optimal female reproductive health and reduces the risk of infertility. (10)

A healthy lifestyle includes not only a nutrient-rich and balanced diet but also physical activity, which can help maintain a healthy weight and reduce the risk of chronic diseases. (8)

stress

Stress can contribute to infertility. Infertile women* experience symptoms related to anxiety and depression more frequently than fertile women*. These characteristics lead to a state of psychological stress that can alter egg maturation. (10)

Vitamin D and folic acid

Recent findings from clinical studies suggest that vitamin D may influence aspects of fertility in both women and men. These include the maturation of eggs and the uterine lining in women, the production and maturation of sperm in men, and the production of sex hormones in both sexes. (9)

However, when supplementing with vitamin D, attention must be paid to the dosage, as an excessive dose can lead to symptoms of poisoning. (8, 11)

The daily requirement for folic acid, also known as vitamin B9 , is 60 to 600 µg, and 550 µg during pregnancy. Pregnant women should therefore take 400 µg daily, especially during the first twelve weeks. Significant overdoses can lead to agitation, nausea, and gastrointestinal disturbances. (15)

caffeine

High doses of coffee may affect fertility by impairing sperm quality, ovulation, or menstrual characteristics (8).

alcohol

Clinical studies have shown that occasional alcohol consumption does not impair fertility. However, the data are not yet conclusive. The influence of alcohol consumption on reproductive outcomes has been investigated in several studies, but so far no significant association has been found between alcohol consumption and the maturation and fertilization of egg cells in women*, nor between alcohol consumption in men and the rate of pregnancy loss. (10) Other sources indicate that daily alcohol consumption, on the other hand, negatively affects sperm quality and sperm volume in men*. (8)

nicotine

In women*, smoking is associated with a rapid decline in ovarian reserves, delayed conception, an increased risk of spontaneous miscarriage, and a lower success rate in artificial insemination.

In men*, the percentage of sperm with normal morphology and motility is significantly reduced. (10)

Tips for getting pregnant

• Regular, unprotected sex (every two to three days), ideally around the time of ovulation, increases the chances of pregnancy. Your best chance of getting pregnant is if you have unprotected sex the day before you ovulate.
• Healthy and balanced diet.
• Avoiding stress.
• Taking folic acid, possibly vitamin D supplementation (pay attention to the dosage).
• If necessary, check adrenal and thyroid hormone levels.
• Avoid excessive consumption of alcohol, caffeine, and nicotine.

Why can't I get pregnant?

Unfortunately, not all couples are lucky enough to conceive quickly. The probability of pregnancy for women* between 18 and 30 years of age is approximately 20 to 30 percent per cycle. With increasing age, it drops significantly and is only about 10 to 15 percent per cycle for 35-year-olds. (12)

Various causes lead to infertility (13, 14):

• Sperm defects or disorders (~30%)
• Ovulation disorders (~25%)
• Unexplained infertility (~25%)
• Fallopian tube problems (~25%)
• Endometriosis (~5%) (= displaced uterine lining outside the uterus)
• Uterine abnormalities (e.g., fibroids) (rare)

If you have an unfulfilled desire to have children, it is advisable to clarify the causes with a gynecologist and to seek detailed advice.

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