Why do triplets have preterm labor?

Basic mechanics occ. Whether it contains triplets, one big baby or extra amniotic fluid, the uterine muscle can only stretch so far before it starts to contract. Similarly fibers holding the cervix closed can only withstand so much weight and pressure before it begins to thin and to open up. A similar thing might happen to a single amniotic sac these (contractions, dilating, bag breaking) can lead to labor, delivery.
1. The human uterus is design to allow the development of a single baby at term. Thus, even twin gestations are considered high risk pregnancies. By a matter of physics, in order to accomodate more than one developing baby, the uterus contracts leading to preterm labor.
Balloon uterus. Think of the triplet uterus as an overdistended balloon filled with water and active babies. It is bound to strecth to the point of no return and start contracting in response. Mechanical stretching is thus the reason for preterm birth in most triplets (average delivery at 32-34 weeks).
More pressure. Three babies take up more room than 1. The uterus is only designed to hold so much. As the triplets grow it soon gets to be "too crowded" the the uterus decides it is time to go. Same things happens with twins but typically that doesn't happen as early as triplets.

Related Questions

What factors affect or increase the risk of preterm labor with triplets? E.G. Weight, age, etc

Triplets. The biggest risk factor for preterm delivery with triplets is - having triplets. I'm not a maternal-fetal specialist, but as an rei i've seen this alot - the main risk factor is the triplet; age, weight, etc, contribute a very small risk above and beyond. Read more...
None/triplets suffic. No other factors are required; triplets in and of themselves will increase the risk of preterm birth tremendously. In fact the mean gestational age at triplet birth is 32 weeks and ~100% of triplets deliver prematurely. As you can tell all other risk factors pale in comparison. There is no evidence that cervical cerclage or Progesterone can prevent preterm birth in twins or higher multiples. Read more...

What can I do to delay preterm labor? I'm pregnant 15 weeks with triplet

Close monitoring . Triplets must be monitored very carefully. You should be a seeing an obgyn with experience dealing with multiples. Cervical length by ultrasound can be done serially. Fetal fibronectin can be done to help predict the risk for preterm labor. Choose and experienced doctor to guide you through the process. Read more...
Rest no stress. You clearly have a very high risk history and you need to be monitored almost weekly closely BP blood sugar level weight. Gain nutrition avoid any physical and mental personnel family stress if you work best would be to take a leave of absence especially if your work is physically demanding your hemoglobin of 8.5 needs to be monitored very closely. Read more...

Pregnant with triplet. Have history of preterm labor 29 weeks (twins) due to rupture membrane. Is it important to do cervical cerclage? (cervix is fine)

Hmmmm. . Let's see. You had preterm labor at 29 weeks with twins and are pregnant with triplets? I'd go for cerclage given the risk of an incompetent cervix is present with 3 babies. I'm guessing you see a perinatologist? If that's what she/he is recommending, i'd sign up for it. Good luck. Read more...

What happens if I go into preterm labor?

Depends. If you act quickly and do not rupture your membranes, the doc can stop your labor with meds and give baby more time to develop. If you do nothing, you will go into labor early and likely end up with a baby in intensive care. Read more...

What are the symptoms of preterm labor you notice first?

Cramping/Contrations. Cramping and contractions are common. Tightening of the abdomen can also be noted. Rhythmic back pain, pevlic pressure, change in vaginal discharge, spotting or bleeding, or large gush of fluid can also be a sign. In any case where there is concern, the pregnant woman should seek immediate care with her OB provider or at an OB facility. Read more...

I don't understand why I went into preterm labor? What are the causes?

Largely unknown... Pretem labor is a blanket/umbrella diagnosis for a wide spectrum of conditions that result in fetal stress and uterine contractions. Such conditions include: infections, poor growth, placental failure, bleeding, too much amniotic fluid, multifetal pregnancies, trauma, fetal anomalies causing hydrops or heary failure, etc. Most of the time there is no diagnosis and preterm labor is "idiopathic". Read more...

Will having amnio cause preterm labor?

Unlikely. The chances are very small. Usually by the mid 30s the risks of an amnio are lower than the risks of the regnancy itself. Read more...
It can. Amniocentesis involves introducing a fine needle into the pregnancy sac to retrieve some amniotic fluid for fetal dna testing. That technique had inherent risks for complications, including preterm labor and preterm premature rupture of membranes. The risk for any of these complications to occur is <1%, but is real and devastating if they do occur. Read more...

Can mag withdrawal cause preterm labor?

Preterm labor. Premature labor is caused by inflammation or infection. Magnesium has been used for the treatment of premature labor, but multiple studies have shown that it doesn't really stop contractions. Its use for this indication is declining. Withdrawing an ineffective medication can't cause premature labor. Read more...
Nope. There is no such thing as magnesium withdrawal! magnesium is an electrolyte normally present in our bodies that has been found to have several beneficial effects during pregnancy when administered in supraphysiologic doses. It can relax the uterus and stop preterm labor for 48 hours but is not approved for longer-term tocolysis. Preterm labor occurs and recurs on the basis of intrauterine status. Read more...