Multiple pregnancies guide weeks 13-16
Your babies are now developing fingernails and toenails, and are
growing very rapidly. Your belly will probably already be quite
rounded, particularly if this is not your first pregnancy. One of
the ways that your LMC will use to check your babies' growth at
your antenatal appointments is by measuring your fundal height.
Your fundal height is the measurement from the top of your uterus
to your pelvic bone. In a singleton pregnancy, the measurement
usually corresponds to the number of weeks pregnant you are, for
example at 30 weeks, your fundal height will be around 30cm.
However in a twin pregnancy, your uterus grows much faster and will
be much bigger. At 13 weeks, your fundal height may be around 20cm
or so. Later in your pregnancy you can expect to measure between
five and ten weeks ahead of your dates, which means that by 30
weeks your fundal height will be the equivalent of a singleton
pregnancy at full term!
Your babies will now weigh around 65g each and be approximately
10cm long. Up until now, pregnancy hormones in your body
have been providing them with nutrients, but early in the second
trimester the placenta (or placentas) take over this function. As a
result, the levels of hCG and other pregnancy hormones in your
blood begin to stabilise and you may find you feel less tired
and that your morning sickness begins to ease. However for a
few women expecting twins, morning sickness will continue
until later in the second trimester, or even until their
babies are born.
If you are expecting monochorionic (identical) twins you will
probably have fortnightly growth scans from around 14 weeks to make
sure that your babies are growing at similar rates. It is normal
for one baby to be slightly larger than the other even from very
early on, but on a larger scale uneven growth can be an indicator
of Twin to
Twin Transfusion Sydnrome (TTTS). TTTS is only a risk when
twins share a placenta, so if your twins are dichorionic (have
their own separate placentas) then you won't need to have these
fortnightly growth scans until later in your pregnancy.
You will continue to have monthly visits with your LMC up until
around 28 weeks if you have no complications, and after that your
visits will be fortnightly, and then weekly. At these visits your
LMC will check your blood pressure and do a dip stick urine test to
check your urine for sugar and protein. He/she will also measure
your fundal height and ask about any concerns you have had over the
past month. Your LMC will also listen to your babies heartbeats
with a handheld doppler. If your LMC is an obstetrician he/she may
even have an ultrasound machine in their clinic so you can see your
babies moving around.
You are now four months pregnant, and your babies are developing
rapidly. Their kidneys will be beginning to function, and their
skin is also forming, although at this stage it is transparent.
Now is a good time to think about whether you would like to
attend antenatal classes. In some of the main centres there are
special antenatal classes available for expectant parents of
multiples to help prepare you for possible complications in your
pregnancy, and for the birth of your babies, as well as what to
expect in the early days after you bring your babies home. Your LMC
or local Multiple Birth Club will be able to give you
contact details for classes in your area.
If you live in an area where there are no multiples-specific
antenatal classes available, you might like to consider
attending standard classes to help prepare you for the birth. Bear
in mind that such classes are usually held over a six-week
period, and as there is a high possibility your twins may be
born prematurely you should start your antenatal
classes soon to ensure you finish them before your babies are