Twin Pregnancy Week 4: Symptoms, Baby Size, Body Changes & more

4 Weeks Pregnant with Twins or Multiples

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Dr. Sanjana Sainani (Gynecologist/Obstetrician)
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On discovering the pregnancy news and knowing that she has entered the 4th week, most first-time mothers would be eager to know how their baby is growing. Many women look for signs of twin pregnancy at 4 weeks and wonder if multiple babies are gestating within them.  Ideally, anytime between the 10th and the 14th week of your pregnancy, you should be able to get a confirmation on whether you’ll have twins or multiples. This article will discuss the implantation of multiple/twin embryos and their growth in the 4th week of pregnancy. Read on to know more.

Implantation of Twin or Multiple Embryos at 4 Weeks

Around the 4-week mark, the eggs that the sperm fertilised reach the uterus and begin the implantation process. If there are multiple embryos, these usually occur when more than one egg is released from the ovaries and fertilized by the sperms, forming fraternal twins or triplets. At times, a single egg splits into multiple ones, leading to the formation of identical twins or triplets. These eggs make their home in the uterus, and the embryos grow.

Baby Growth in the 4th Week of Pregnancy

As you begin completing the 4th week of pregnancy, the neural tubes of the babies present in the uterus begin to form. These mark the initial phase for the nerves, spinal cord, vertebrae, and brain to stem from and begin to grow. The circulation system also begins to get a growth impetus, as the arteries and hearts start forming. Umbilical cord formation and functioning begin around this time, too.

Pregnacy 4 weeks baby growth

What Size Are the Babies at 4 Weeks of the Pregnancy?

The baby that is present within the uterus is still in the embryonic stage. It is as tiny as a seed (almost 1/25th of an inch, to be precise), while all the physical and inner developments are going on speedily within it. Pretty soon, slight features of the face and the presence of limbs will start appearing over the coming week.

Your body would go through a series of changes after you conceive. Let’s take a look at some of the common changes.

Common Body Changes in Mothers-To-Be

For many women, the 4-week mark officially confirms pregnancy and flags of the journey for them. Some specific body changes that occur at this stage are:

  • As the embryos get implanted within the uterus, some women tend to experience light bleeding or spotting. Once the egg has been implanted, the lining of the uterus thickens itself to keep the baby safe, which may cause bleeding and some pain.
  • The placenta will have started forming ar week 3 already. In the 4th week of pregnancy, it will continue forming further.
  • The mucus in the cervical region begins to increase and close it up in the form of a plug, which will stay until the baby is fully grown and ready to be delivered.
  • This also might be the time when some women will miss their period for the first time and be might get themselves tested to confirm the pregnancy. Combined with nausea and vomiting sensations, these hopes will be fully confirmed.
  • Some mothers-to-be also experience darkening of the areolas as well as increased sensitivity and tenderness in the breasts.

Couple checking pregnancy test

Let’s take a look at what the pregnancy test would confirm at 4 weeks.

Pregnancy Test At 4 Weeks

Undergoing a twin 4 weeks pregnancy ultrasound might help some doctors confirm their presence, but it generally may not be the result. Despite having the embryos within them, many women won’t even get a positive pregnancy test at this stage. This is primarily due to the hCG hormone levels not being high enough to trigger the pregnancy test result. The hCG hormone also restricts the release of any further eggs since pregnancy has been attained, indirectly boosting progesterone and estrogen levels. All these effects work in tandem to prevent a period and stop ovulation. Allow yourself the time of at least one week from your expected day of the menstrual cycle to get a pregnancy test done for conclusive results.

So, we know that, at 4 weeks of pregnancy, it is impossible to identify if a woman will have twins or multiples. However, many believe pregnancy symptoms could suggest she carries twins or multiples.

Symptoms of Twin or Multiple Pregnancy at 4 Weeks

Compared to other women, those who are pregnant with twins or multiple babies could have stronger signs of pregnancy early in their cycle. Some of the strongest symptoms are:

  • A stronger sensation of nausea combined with a frequent urge to urinate.
  • Overwhelming exhaustion all of a sudden as well as increased soreness and swelling of the breasts.
  • During this time, bloating, cramping, fatigue, mood swings, and spotting will also be seen.
  • Women carrying twins or multiples may experience more pronounced fatigue than those carrying a single baby. 
  • Needing to urinate more frequently than usual is another symptom in multiple pregnancies due to the increased blood flow to the pelvic region and the expanding uterus’s growing pressure exerted on the bladder.

Extreme nausea at 4 weeks

Most of these changes could primarily be because of the presence of multiple embryos, which tends to shoot up the levels of progesterone, estrogen, estradiol, and the HCG hormone in the body.

Whether you are pregnant with twins/ multiples or not, you must take care of your health once your pregnancy is confirmed. Here are some tips that you may follow for a healthy and happy term.

Pregnancy Care Tips

There are a few tips women who are 4 weeks pregnant with twins belly should adhere to:


  • Have a repeat pregnancy test if your previous one turns out to be negative.
  • Start a dose of prenatal vitamins.


prenatal vitamins at 4 weeks


1. Does a Strong Positive Line on a Pregnancy Test At 4 Weeks Mean Twins?

No, a solid positive line on a pregnancy test does not necessarily indicate twins. The strength of the positive line is typically determined by the concentration of the pregnancy hormone hCG (human chorionic gonadotropin) in your urine. However, the level of hCG can vary among individuals and is not specifically indicative of a multiple pregnancy. To confirm the presence of twins, an ultrasound examination performed by a gynaecologist is the most reliable method.

2. What Is the Range of Hcg Levels for Twins?

The range of hCG levels in multiple pregnancies, including twins, can vary widely. No definitive hCG level can determine the presence of twins with absolute certainty. However, hCG levels are generally higher in multiple pregnancies than in singleton pregnancies. The exact range of hCG levels can depend on factors such as gestational age, individual variations, and other circumstances unique to each pregnancy.

Being pregnant with multiple babies in the belly can be enticing for any woman. But, each woman will have a different experience while their little ones grow inside them. Make the best of it and care for yourself since you are on a journey.


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Next Week: Twin Pregnancy Week 5

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