<a href="https://en.wikipedia.org/wiki/Biparietal_diameter" class="extiw" title="en:Biparietal diameter">Biparietal diameter</a> of a fetus by <a href="https://en.wikipedia.org/wiki/gestational_age" class="extiw" title="en:gestational age">gestational age</a>, with the blue line representing the <a href="https://en.wikipedia.org/wiki/mean" class="extiw" title="en:mean">mean</a> and the green area representing the 90% <a href="https://en.wikipedia.org/wiki/prediction_interval" class="extiw" title="en:prediction interval">prediction interval</a>. 
<p>Reference:
</p>
<ul><li><cite style="font-style:normal"> (Jan 1994). "Fetal biometry at 14-40 weeks' gestation.". <i>Ultrasound Obstet Gynecol</i> <b>4</b> (1): 34-48. <a href="https://en.wikipedia.org/wiki/Digital_object_identifier" class="extiw" title="w:Digital object identifier">DOI</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1046/j.1469-0705.1994.04010034.x">10.1046/j.1469-0705.1994.04010034.x</a>.</cite></li></ul>
In addition to data taken from this study, the diagram is extrapolated from 0 to 14 weeks of gestational age by the rationale that it is 0 by fertilization at 2 weeks of gestational age.
<a href="//commons.wikimedia.org/wiki/User:Mikael_H%C3%A4ggstr%C3%B6m" title="User:Mikael Häggström">Mikael Häggström</a>
<span class="int-own-work" lang="en">Own work</span>