The question of how to have twins has no definite answer. As fascinating as it may be, the chances of giving birth to twins are often purely random. Different factors, such as genetic or medical procedures, may induce a twin or multiple pregnancies. However, there cannot be a 100% guarantee despite different methods.
Read on as we tell you about the chances of conceiving twins, including factors to increase the probability and different fertility treatments that might help you with the same.
How Are Twins Conceived?
There are two types of twins – identical (non-fraternal) and non-identical (fraternal) (1).
Nearly one-third of twins are identical twins, also known as monozygotic twins. They happen by chance and develop when one egg is fertilized by one sperm and gets divided into two separate embryos. They share the same genetic composition and placenta. Identical twins can also happen in women who undergo fertility assistance methods.
Non-identical, also known as dizygotic twins, develop when two eggs are fertilized by two sperms. They are unique and do not share the genetic composition or placenta. As non-identical twins share only half of the same genetic makeup, they are not always of the same gender.
General Odds Of Having Twins
The 21st-century statistics show that the possibility of having twins are 3%, i.e., 3 in 100 among the general population. Figures also show that there is an increase of almost 61% from the early 1980s. A much recent update from the US National Center for Health Statistics says that the twin birth rate is 33.9 per 1000 live births (2).
Factors That Determine The Chances of Having Twins
As said earlier, identical twins could only happen by sheer chance. But certain factors might influence the chances of having fraternal twins.
1. Family history / Heredity
If you are a twin or twins run in your family, you are more likely to have twins. However, if your partner has a twin or there are twins in their family, it is not going to influence your chances or having or not having twins.
It all depends on you, because you produce the eggs. If you or your mother is a twin, the probability of you having twins is high. You may have higher chances of hyperovulation (releasing two eggs during ovulation process). A few specific genes combine with hyperovulation and thus increase the frequency of non-identical twins (3).
2. Ethnicity / Race
Your origin is also believed to have a strong influence on your chance of having twins. Asians and Hispanics have fewer chances of producing twins, whereas Africans are highly probable, followed by Europeans.
3. Type of body (height/weight)
Although strange, it is said that taller women are more likely than shorter ones to conceive with twins. Also, heavier women have higher chances than thinner women.
Women who have a well-nourished diet might be at a higher probability of producing twins than those who have a reduced and low-fat diet.
A research study published by the American College of Obstetrics and Gynaecology states that the increasing rates of multiple births are due to increased rates of obesity. It is found that women with a body mass index (BMI) of 30 and above are more likely to produce twins. This holds for only fraternal twins (4).
4. Maternal age
Your chance of having twins or more babies may increase with advancing age. Women above 35 years produce more FSH (follicle-stimulating hormone) than younger women (5). This hormone allows the ovaries to release eggs for ovulation. The higher the hormone levels, the more the eggs released during ovulation are, thereby resulting in multiple fetuses.
5. More pregnancies
If you had multiple pregnancies before, there may be a high chance of producing twins. The probability of twins might also improve with the increasing number of pregnancies.
Fertility Treatments To Have Twins
Fertility treatments provide better chances for having twins. Your doctor can suggest the best option for you. However, experts discourage multiple babies through fertility treatments.
1. IVF (in vitro fertilization)
Women who undergo IVF may have fair chances of giving birth to more than one baby. However, it mainly depends on the number of embryos placed in the uterus.
To increase the odds of twin conception, the healthcare experts might place more than one embryo into the womb. If both are implanted and developed successfully, it is likely to result in twin pregnancy.
2. IUI (intrauterine insemination)
In this procedure, the sperms are injected into the uterus using a syringe. However, IUI alone will not increase the chances of having multiples. Women who undergo this treatment may have to take fertility drugs to increase the likelihood.
These medications might improve the chances of having twin babies as they enhance the overall health of eggs and their maturity. Gonadotropins are likely to stimulate the release of more than one egg at a time (5). Your doctor can prescribe the right one for you.
5. Clomiphene citrate
There is around 10% chance of producing twins with Clomiphene or Clomiphene citrate (6). Women who already have higher probability or twin births may also improve their chances further with this drug
The pill may be taken before trying assisted reproductive treatments like in vitro, to promote egg production.
It might also help treat hormonal imbalances in men, which may affect the quality and quantity of sperm, and their motility.
Fertility Herbs For Twins
Although there is no science supporting the use of herbs for twin conception, alternative forms of medicine, such as Chinese and Ayurvedic medicine still encourage using certain herbs for fertility and conception. Again, there is no direct evidence about how well they could promote twin or multiple pregnancies.
- Evening primrose oil is believed to promote healthy cervical mucus that might allow the sperm to survive within the ovary for a longer time.
- Licorice is said to control hormonal levels of estrogen and testosterone, and might support conception.
- Flaxseed oil is likely to boost fertility and might increase chances of twin conception.
- Sweet cassava is also said to increase the chances of twins due to its hyper-ovulation properties.
- Black cohosh is not known to increase the chance of twin conception, but it is believed to increase the fertility rate.
- Vitex (chaste tree berry) might regulate hormonal levels, promote ovulatory function, and may prevent ovarian cysts, all of which are thought to be favorable for twin conception.
- Maca root is also believed to improve overall fertility that might improve the chances of having twins.
Although these herbs are natural, they do carry some possible side effects. Therefore, it is advisable to check with an experienced herbalist or a naturopath before trying them.
Natural Ways That Might Improve Chances Of Conceiving Twins
The following options are likely to boost your chances of having twins. However, they are just common beliefs based on anecdotal evidence and do not have any scientific backing.
1. Dairy products
Women who eat dairy are likely to increase their chances to produce twins than women who do not consume these products. It is thought that the growth hormones present in milk (dairy from growth hormone-treated cows) may help in having twins
2. Wild yams
Wild yams are said to hyper-stimulate the ovaries, resulting in the release of more than one egg for ovulation. It may, therefore, increase your chances of producing twins. African women are believed to have better chances for twins because they consume it as a part of their ethnic diet. The Yoruba tribe in West Africa has the highest twinning rate (7).
3. Stop birth control pills
When you stop taking the birth control medication, your body takes some time to find its natural rhythm. One study report states that there is a chance of conceiving twins within a year of stopping oral contraceptives (8).
4. Pregnancy while breastfeeding
A study found out that women who conceived while breastfeeding were more likely to have twins (9).
5. Have your partner eat zinc-rich foods
Zinc is known to improve sperm levels. So you could ask your partner to include foods such as pumpkin seeds, lamb, green peas and yogurt, which are rich in zinc (10). It might increase the probability of fertilizing more than one egg.
6. Have space between pregnancies
Your chances of conceiving twins may be higher if you have enough gap between your pregnancies.
Do Certain Sex Positions Help Conceive Twins?
Though it is believed that some sex positions might help achieve twin pregnancy, there are no scientific studies to support these claims. Some of the positions that are believed to help you conceive twins, based on people’s beliefs and myths, are as follows:
1. Side by side
Known as doggy style, it is thought to boost a woman’s chance of conceiving twins as the cervix is more approachable to the sperms in this position.
2. Standing up position
It is also another doggy style and is believed to have a chance of deep penetration, which may influence your chance of having twins.
3. Missionary position
The man-on-top position is also thought to help the sperm to enter the egg easily, and probably help produce twins.
4. Rear entry position
Here, the partner enters from behind, so it is believed that the sperm remains close to the cervix of the woman, affecting the chances.
Frequently Asked Questions
1. Can I have twins through natural birth?
Yes. Although many women believe that twins can only be born through C-section delivery, more than 40% of women give birth to their twins naturally (vaginal birth) (11).
2. When are twins usually delivered?
Most twins get delivered between 32 and 38 weeks, depending on the pregnancy conditions (12).
3. Do twins skip a generation?
Since twin birth is influenced by factors such as genetics, maternal height, and medical interventions, the popular belief that twins skip a generation is false. People may believe this myth because men inherit their genes from their mothers. They may then pass this gene to their daughters, who may give birth to twins in the next generation (13).
Having twins is a delightful experience, but there is no sure-shot way to get pregnant with twins. Heredity, race, and maternal age are some factors that can positively influence your chances of having twins. IVF and IUI are assisted reproductive methods that can help you conceive multiple babies, though using these methods to conceive multiple babies is strongly discouraged by experts. Some herbs, such as black cohosh and licorice, certain foods, and sex positions are thought to help in twin pregnancy. However, no clinical evidence exists to support these beliefs. Having twins is a matter of sheer luck.
2. Births: Final Data for 2017; National Vital Statistics Reports; CDC/National Center for Health Statistics (2018)
3. Is the probability of having twins determined by genetics? Genetics Home Reference (NIH)
4. Reddy UM et al.; Relationship of maternal body mass index and height to twinning; Obstet Gynecol. (2005)
5. Chorionic Gonadotropin; APP Pharmaceuticals LLC (2011)
6. Fertility Treatments for Females; NIH (2017)
7. A. Akinboro et al.; Frequency of twinning in southwest Nigeria; Indian J Hum Genet. (2008)
8. M F Murphy et al.; Is there an increased risk of twinning after discontinuation of the oral contraceptive pill; J Epidemiol Community Health. (1989)
9. Steinman G; Mechanisms of twinning. IV. Sex preference and lactation; The Journal of Reproductive Medicine; Europe PubMed Central (2001)
10. I have a low sperm count. Can I do anything to increase my fertility? SexInfo; University of California, Santa Barbara
11. Giving birth to twins or more; NHS
12. Twin Pregnancy: Answers from an Expert; Johns Hopkins Medicine
13. 5 Proven Ways to Tell if You’ll Have Twins; Creating a Family